Law of Indonesia is based on a civil law system, intermixed with local customary law and Dutch law. Before the Dutch presence and colonization began in the sixteenth century, indigenous kingdoms ruled the archipelago independently with their own custom laws, known as adat (unwritten, traditional rules still observed in the Indonesian society).^[1] Foreign influences from India, China and the Middle East have not only affected culture, but also the customary adat laws. The people of Aceh in Sumatra, for instance, observe their own sharia law, while ethnic groups like the Toraja in Sulawesi still follow their animistic customary law.

Dutch presence and subsequent colonization of Indonesia for over three centuries has left a legacy of Dutch colonial law, largely in the Indonesian civil code and criminal code. Following independence in 1945, Indonesia began to form its own modern Indonesian law, modifying existing precepts. Dutch legal decisions maintain some authority in Indonesia through application of the concordance principle. The three components of adat, or customary law; Dutch law; and modern Indonesian law co-exist in the current law of Indonesia.

Indonesian legislation comes in different forms. The following official hierarchy of Indonesian legislations (from top to bottom) is enumerated in Article 7 of Law No. 12/2011:^[2]

1. The 1945 Constitution (Undang-Undang Dasar Negara Republik Indonesia Tahun 1945 or UUD 1945);
2. Resolutions of the People's Consultative Assembly (Ketetapan Majelis Permusyawaratan Rakyat or Tap MPR);
3. Acts (Undang-Undang or UU, also translated as Laws) and government regulations in-lieu-of Acts (Peraturan Pemerintah Pengganti Undang-Undang or Perppu);
4. Government regulations (Peraturan Pemerintah or PP);
5. Presidential regulations (Peraturan Presiden or Perpres);
6. Provincial ordinances (Peraturan Daerah Provinsi or Perda Provinsi); and
7. City ordinances (Peraturan Daerah Kota or Perda Kota) and Regency ordinances (Peraturan Daerah Kabupaten or Perda Kabupaten).

In practice, there are also presidential decrees (Keputusan Presiden or Keppres), presidential instructions (Instruksi Presiden or Inpres), ministerial regulations (Peraturan Menteri or Permen), ministerial decrees (Keputusan Menteri or Kepmen) and circulars (Surat Edaran or SE), all of which are legally binding and sometimes in conflict with each other.

Once a legislation is promulgated, a State Gazette of the Republic of Indonesia (Lembaran Negara Republik Indonesia) is issued by State Secretariat. Sometimes elucidation of the legislation (Penjelasan) or attached documents like charts accompany the main legislation in a State Gazette Supplement (Tambahan Lembaran Negara Republik Indonesia). The Government also produces State Reports (Berita Negara, lit. 'State News') to publish government and public notices as well as other ministerial regulations and decrees.

Main sources of law for Indonesian criminal law come from the criminal code (Kitab Undang-Undang Hukum Pidana) and the criminal procedural code (Kitab Undang-Undang Hukum Acara Pidana). Other rules concerning a more specific subject on criminal actions may come from Acts and other regulations. The criminal code is a localized, translated version of Dutch colonial criminal code, the Nederlandsch-Indische Wetboek van Strafrecht which in turn was based on French Penal Code of 1810 and Wetboek van Strafrecht (Nederland). The criminal procedural code is post-colonial, enacted into law in 1981.

Under the previous pre-2023 Criminal Code, Indonesian criminal legal system recognized two types of criminal acts: the heavier crimes (Kejahatan or Misdrijven) and the lesser misdemeanors (Pelanggaran or Overtredingen).^[30] However this distinction is abolished with the new Criminal Code enacted in 2023.

Indonesian legal system utilizes the Civil Code (Kitab Undang-Undang Hukum Perdata or KUHPer, previously known as Burgerlijk Wetboek or BW), as well as two civil procedural codes: Herzien Inlandsche Reglement or HIR for civil cases in Java and Madura, and Rechtreglement voor de Buitengewesten or RBG for civil cases outside Java and Madura.^[36] There is also the Commerce Code (Kitab Undang-Undang Hukum Dagang or KUHD previously known as Wetboek voor Koophandel) used for basic commercial principles. The Civil Code, the Commerce Code, and both civil procedural codes are Dutch colonial legal codes, directly adapted from Dutch laws. Other rules concerning civil law may come from newer, more specific Acts and other regulations.

Rules on marriage in Indonesia are stipulated mostly under the 1974 Marriage Act (Undang-Undang No. 1/1974 tentang Perkawinan) and has largely unchanged, safe for an amendment in 2019 and three constitutional reviews in 2010^{[note 1]}, 2015^{[note 2]}, and 2017^{[note 3]}.^[37][38] The Act itself repealed several articles on family and marriage previously covered in the Civil Code, as well as repealed colonial laws on Mixed Marriage (Reglement op de Gemengde Huwelijken) and special rules for marriage of native Christians (Huwelijke Ordonantie Christen Indonesiers), creating a post-colonial outlook and approach on family law in Indonesia.^[39] In addition, some rules are also added through the official Indonesian Compilation of Islamic Laws (Kompilasi Hukum Islam), a set of general Sharia laws and principles in private laws, applicable and compatible with Islamic practices in present-day Indonesian Muslim society.^[40]

In summary:

• The act of marriage in Indonesian law is a spiritual union of man and woman, legal if it is lawful under each parties' religious rules of marriage. Such marriage then will be acknowledged by state and will be registered in the civil registry.
• All marriage by principle are monogamous. However, polygynous marriage is allowed under strict limitations, such as if the wife is unable to conceive or unable to exercise her family duty as a wife. Most importantly, the wife must be present and give the husband her permission to marry again. Meanwhile, polyandrous marriage is not allowed.
• Marriageable age is 19 for both man and woman. Prior to the 2017 constitutional review and 2019 amendment of the Act, it was 19 for man and 16 for woman. It was altered due to conflicting rules with another law which define a child as being under 18 years of age, including unborn child. However the Act still allowed the record of marriage involving parties below the marriageable age, if the parties request and receive a court dispensation (from the Religious Court if Muslim, from the District Court if other than Muslim).
• Marriage can be annulled by both husband and wife, or their parents, or an appointed official. Annulment is allowed if the marriage is found to be unlawful under religious laws or the civil law, or if the marriage is concluded under unlawful threat, or if one party discovered undisclosed personal matters regarding the other party. The time period and conditions for annulment is not unlimited, however; Different time limit applies for different conditions.
• Nuptial agreements (perjanjian perkawinan, lit. 'marriage agreement'), a legal term used in the Act to describe an agreement concluded between the parties, is encouraged and allowed to be concluded either before marriage, during the wedding ceremony, or after the wedding during the rest of the marriage. Prior to the 2015 constitutional review of the Act, nuptial agreements are limited to only those concluded before or during the wedding.^[41]
• Property acquired during marriage is considered joint ownership marital property. Property acquired before marriage by each parties are of their own, unless specified otherwise.
• Dissolution of marriage is only caused by death, by divorce, or by court decisions. The act of divorce is concluded in court hearings (Religious Court for Muslims, District Court for other than Muslims), after all attempt to solve the differences fail. Reason to divorce is limited by law:^[42]
  • A party committed adultery, or become alcoholic, drug abuser, or addicted to gambling;
  • A party abandoned the household for two continuous years without reasonable cause;
  • A party committed a crime and punished by incarceration for five years or more;
  • A party mistreated, abused, or endangered the other party (domestic abuse);
  • A party suffered from physical disability or disease, which render the party unable to exercise their family duty;
  • Continuous quarrels between husband and wife which render the parties unable to continue their marriage.
  • Under the official Indonesian Compilation of Islamic Laws, two more reasons for divorce is stated: (1) The husband violated the sighat taklik talak (marriage oath read by the husband in Islamic wedding), and (2) A party later converted to different faith, which may cause a crisis of faith in the household.
• The Act also regulates on Child. Children born in marriage or born as a result of a lawful marriage are lawful children. Children born out of wedlock have automatic familial relations to the mother and the mother's family, as well as the father, proven by paternity test. Prior to the 2010 constitutional review of the Act, children born out of wedlock only have familial relations to the mother, but no rules on the father.^[43]
• Children under the age of 18 are under their parents' protection and care, and they represent their children within and outside the court of law. Exception are made for children who are already married before the age of 18, they are to be considered adult.
• Guardians (wali) can be assigned guardianship over children under the age of 18, who are never married, and not under their parents' protection and care. Guardians also serve as caretaker over the children's property, and continue to do so until the children reach the age of 18 or considered an adult by virtue of marriage.
• Parents (and Guardians) can be stripped of their parental (or guardianship) authority by request of one of the parent, the grandparents, full siblings who already reached adulthood, or appointed officials. The reason for this action may be due to parental (or guardianship) neglect, or they are considered to be behaviorally unbefitting. Parent(s) who are stripped of their authority must still continue the support payment for their children. Guardians who are stripped of their authority will be replaced by court-appointed guardians.
• Marriage concluded overseas between Indonesian citizens or when one party is an Indonesian citizen is lawful if (1) The marriage itself is considered to be lawful under the law where the marriage is concluded, and (2) The Indonesian citizen(s) in this marriage got married lawfully under the Act. Vice versa, marriage concluded in Indonesia between an Indonesian citizen and a foreign citizen is also lawful under the same conditions. Only this latter type of marriage is formally known as Mixed Marriage (Perkawinan campuran) under the Act, and it is one option for foreigners to acquire Indonesian residence permits and citizenship.^[39]

Indonesian commercial law utilizes several sets of laws, starting with the colonial Commerce Code. The Commerce Code repealed and replaced many articles regarding commercial and corporate activities in the Civil Code. In turn, new laws and regulations would be enacted to repeal and replace older rules from the codes, as well as to introduce new norms and rules, such as the Limited Liability Company Act of 2007 (Undang-Undang No. 40/2007 tentang Perseroan Terbatas).^[47]

The Commerce Code introduces several type of business entities (Badan Usaha):

• Sole Proprietorships (Perusahaan Perseorangan), where business is run by individual(s);
• Partnerships (Persekutuan), which includes:
  • Private Partnerships (Persekutuan Perdata or Maatschap), basic partnership formed to run a business, and usually ends when one of the partners left;
  • Firms (Persekutuan Firma, Vennootschap onder Firma, or simply Firma), where partnership runs a business under a common name, and the absence of one partner does not usually end the partnership;
  • Limited Partnerships (Persekutuan Komanditer or Commanditaire Vennootschap), where partners are differentiated between 'active partners' who invest in and run the business, and 'passive partners' who invest in the business, but do not run it. Very similar to Kommanditgesellschaft;
• Limited Liability Companies (Perseroan Terbatas), where business ownerships are divided into shares.

Of all these business entities, only limited liability companies are which to be considered a legal entity at the same time. Indonesian laws also acknowledge separate sets of Legal Entities (Badan Hukum):

• Limited Liability Companies;^[47]
• Foundations (Yayasan);^[48]
• Cooperatives (Koperasi);^[49] and
• Associations (Perkumpulan Berbadan Hukum).^[50]

The agrarian laws in Indonesian are composed mostly regarding land laws, but in the broadest term might include resource management principles on water, mining, fishery, and forestry. The authoritative statute regarding this subject is the 1960 Agrarian Basic Law Act (Undang-Undang No. 5/1960 tentang Peraturan Dasar Pokok-pokok Agraria) or simply the Agrarian Act. Its purpose was to unify the already-existing colonial and various adat rules on land and land use, and transform them into a national land reform framework for a modern agrarian laws.^[52]

In summary:

• All the land, water, and air space of Indonesia, including all resources within it, belongs to the Indonesian nation (Bangsa Indonesia), and the nation authorized the state to control its use and rights over the land, water, air space, and the resources within. It means that claims to 'unclaimed' land or resources will not be acknowledged, as no land is considered res nullius by principle.^[53]
• The state acknowledged both individual and communal ownership over land and resources. The latter (known as Hak Ulayat) is more relevant within the context of traditional indigenous communities of Indonesia, who may still practices communal ownership of goods and resources within their respective community. However these acknowledgement of traditional rights will not overrule national development effort.
• The Act and other regulations set on several rights over the use of land:^[54]
  • Primary rights, where it is directly granted from the nation's right over land (rights granted by the state). It consists of four rights, limited to Indonesian citizens only:
    • Right of Ownership (Hak Milik), which only Indonesian citizens and a limited number of legal entities may acquire it. Foreign citizens, foreign legal entity, and Indonesians with more than one citizenships are excluded from having this right, even if they managed to acquire such right by means of inheritance or by marital joint property. In such situation, within one year they must transfer the rights over the assets to someone lawful or said assets be taken over by the state;
    • Right to Cultivate (Hak Guna Usaha), which only Indonesian citizens and legal entities registered in Indonesia may acquire it. The right authorized its holder to control and use the land for agriculture, plantation, fishery, and/or husbandry purposes;
    • Right to Build (Hak Guna Bangunan), which only Indonesian citizens and legal entities registered in Indonesia may acquire it. The right authorized its holder to construct structure on the land for personal or business use;
    • Right to Use Granted by State (Hak Pakai yang diberikan negara) granted its holder to use the land for personal or business purposes within a certain period of time. The right is granted to Indonesian citizen, legal entities registered in Indonesia, government institutions, religious and social organizations, foreign citizens based in Indonesia, foreign legal entities with a representation based in Indonesia, and diplomatic missions of foreign states or international organizations.
  • Secondary rights, where it is indirectly granted from the nation's right over land (rights granted from the land owners). It consists of:
    • Right to Build Granted by Land Owners (Hak Guna Bangunan yang diberikan pemilik tanah);
    • Right to Use Granted by Land Owners (Hak Pakai yang diberikan pemilik tanah);
    • Right to Land Pledge (Hak Gadai Tanah);
  • Grants, or Waqf, of land and property for the purpose of Islamic worship, education, and social welfare, in perpetuity;
  • Encumbrance rights (Hak Tanggungan) over land, which is a mortgage guarantee attached to land, separate from hipotek, which are mortgage rights over fixed property other than land;
  • Strata titles over condominiums (Hak atas Satuan Rumah Susun), which is subject to 2011 Condominium Act (Undang-Undang No. 20/2011 tentang Rumah Susun); and
  • Other rights yet to be phased out, such as Right to Sharecrop (Hak Usaha Bagi Hasil), Right to Lodge (Hak Menumpang), and Right to Lease (Hak Sewa).

Intellectual Property (IP) laws exist and sufficiently regulated. Several categories of IP rights are acknowledged, regulated, and protected under its own act.

Trademarks

Marks (Merek) are two- or three-dimensional visual signs represented with images, logos, names, words, letters, numbers, sets of colors, sounds, holographic imageries, or any combinations thereof, created with the purpose of differentiating goods and/or services provided by any individuals or entities, used in any commercial activities.^[55] These marks are to be used for identification of products, promotion of products, quality assurance of products, and marker of products' origins.

A registered trademark's protection lasts for 10 years since the date of trademark authorization, and renewable for extensions.

Trademarks protection is regulated under the 2016 Trademarks and Geographical Indications Act (Undang-Undang No. 20/2016 tentang Merek dan Indikator Geografis).^[56]

Patents

Patents (Paten) are exclusive rights which belong to inventors of technological inventions. Ownership of patents allowed inventors to implement themselves or authorize others to implement the inventions. Inventions (Invensi) are defined as inventors' problem-solving ideas in a technology-specific problems, which may appear as a product, a process, or an innovation and development of said products and processes.^[57] Meanwhile, Simple Patents (Paten Sederhana) are different from normal patents, in which they are improvement of an existing process and products, directly applicable in the industry.

A patent's right lasts for 20 years since the date of patent authorization. A Simple Patent's right may lasts for 10 years since the date of patent authorization.

Patents protection is regulated under the 2016 Patents Act (Undang-Undang No. 13/2016 tentang Paten).^[58]

Industrial designs

Industrial designs (Desain Industri) are defined as a two- or three-dimensional creative works of forms, configurations, or compositions of lines and/or colors, or any combinations thereof, with an aesthetical value and executed into a two- or three-dimensional form, and applicable in the production of goods, industrial commodities, or hand-crafted products.^[59]

An industrial design's right and protection lasts for 10 years since the date of industrial design authorization. The right owner holds exclusive rights to either authorize or to forbid its commercial use.

Industrial designs protection is regulated under the 2000 Industrial Designs Act (Undang-Undang No. 31/2000 tentang Desain Industri).^[60]

Copyrights

Copyrights (Hak Cipta) are exclusive rights of creators over their creative works, automatically exist and enter into force under a principle of declaration after its creation. Within the rules of copyrights, a Related Rights (Hak Terkait) serve as an exclusive rights granted to performers, phonographic producers, or broadcasting bodies who utilized and benefitted from performing, producing, and broadcasting creative works.^[61] Under copyright laws, several creative works are protected, such as:

• Books, computer programs, pamphlets, layouts of published writings, and other creative writings;
• Sermons, lectures, orations, and other related creative works;
• Props made for education and scientific purposes;
• Songs and musical works, with or without lyrics;
• Theatrical dramas, musical dramas, dances, choreographies, puppetries (pewayangan)^{[note 4]}, and pantomimes;
• Fine arts, which include painting, drawing, carving, calligraphies, sculptures, plastic arts, collages, and applied arts;
• Architectures;
• Maps, charts, and other products of cartography;
• Batik techniques;
• Photographs; and
• Translations, interpretations, adaptations, anthologies, and other transformed products.

Several dates of copyright protections exist:

• General copyrights last for the creators' lifetime plus 70 years;
• Computer program copyrights last for 50 years since the first publication;
• Performers copyrights last for 50 years since the first show;
• Phonographic producers copyrights last for 50 years since the first publication;
• Broadcasting bodies copyrights last for 20 years since first airing.

Copyrights protection is regulated under the 2014 Copyrights Act (Undang-Undang No. 28/2014 tentang Hak Cipta).^[62]

Geographical indications

Geographical indications or GI (Indikasi Geografis) are a mark or sign which indicate an origin of produced goods, which due to its geographical elements, may it be natural or manmade, able to attach to those goods a certain reputation, quality, and characteristic.^[63]

Protection of GI rights last for as long as the reputation, quality, and characteristic attached to the goods, all of which are the basis of the GI rights authorization, are maintained.

GI protection is regulated under the 2016 Trademarks and Geographical Indications Act (Undang-Undang No. 20/2016 tentang Merek dan Indikator Geografis).^[56]

Integrated circuit layout designs

Integrated circuit layout designs (Desain Tata Letak Sirkuit Terpadu) are defined as a three-dimensional assembly of a layout design, of which one part of it have to be an active element, also of which all of the interconnects or part of the interconnects of an integrated circuit and the three-dimensional assembly are meant for the creation of an integrated circuit.^[64]

Meanwhile, an integrated circuit or IC (Sirkuit Terpadu) is defined as a produced good, finished or semi finished, of which one part of it have to be an active element, also of which all of the interconnects or part of the interconnects are integrated within a semiconducting material to achieve an electronic function.

An IC layout design protection last for 10 years since the layout design first commercially exploited or since the date of authorization.

The IC Layout Design protection is regulated under the 2000 Integrated Circuit Layout Designs Act (Undang-Undang No. 32/2000 tentang Desain Tata Letak Sirkuit Terpadu).^[65]

Trade secrets

Trade secret (Rahasia Dagang) is a publicly unknown information of technological or business value, which also have an economic value for its usefulness in business activity, and for that it is to be kept secret by its owners.^[66] These trade secrets may include methods of production, processing methods, sales method, or other technological and/or business information, which may have economic value and unknown to the general public.

Protection of Trade Secret rights is regulated under the 2000 Trade Secrets Act (Undang-Undang No. 30/2000 tentang Rahasia Dagang).^[67]

Plant varieties

Plant varieties protection (Perlindungan Varietas Tanaman) is an exclusive right of plant breeders to control materials relating to cultivating a unique plant variety.

Protection of plant variety rights is regulated under the 2000 Plant Variety Protection Act (Undang-Undang No. 29/2000 tentang Perlindungan Varietas Tanaman).^[68]

Communal IPs

With the ratification of Nagoya Protocol, Indonesian IP protection laws beginning to acknowledge communal rights over certain IPs, such as: (1) Expressions of traditional cultures, (2) Traditional knowledge, and (3) Genetic resources. In addition, potential GI rights can be applied under a communal rights belonging to a community.^[69]

Communal IP protection is regulated under the 2017 Law and Human Rights Ministerial Regulation on Communal Intellectual Property Data.^[70]

Rules and regulations regarding the application of international laws in Indonesia are based in the Art. 11 of the Constitution, the 2000 Treaties Act (Undang-Undang Nomor 24 Tahun 2000 tentang Perjanjian Internasional) and 2018 Constitutional Court decision on the Act.^[1][3] International treaties, following its signature or accession by authorized Indonesian officials, need to be debated by the People's Representative Council and ratified into acts. Treaties concerning these following subjects must be ratified by acts:

• Political issues, peace agreements, and matters of national defense and security;
• Territorial changes or border delimitation of Indonesian territory;
• Indonesian sovereignty or sovereign rights;
• Basic human rights and the environment;
• Formation of new legal norms; and
• Foreign loans and/or grants.

Some treaties, however, can be ratified using only presidential regulations, if the subjects of the treaties are not concerning the points mentioned above, or if said treaties are mere procedural and do not need any form of ratification into national legislations (i.e. protocols to a treaty).

There are still many problems with the legal system in Indonesia. Many laws and regulations conflict with each other, and because the legal system (including the courts) sometimes does not operate effectively, it can be difficult to resolve these conflicts. Further, the rule of law in Indonesia is often undermined by rife corruption among the nation's judiciary and law enforcers.^[71]

• Law enforcement in Indonesia
• Indonesian criminal procedure