A preemptive arrest is one in which a person is arrested prior to committing a crime. Preemptive arrests are sometimes viewed with suspicion as being contrary to the principles of a democracy.^[1]

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This practice is distinct from an arrest on a charge of conspiracy to commit a crime, which for example in the United States federal system is itself a crime. A conspiracy charge in this system must be proven beyond a reasonable doubt, and requires that two or more parties have agreed to or planned to commit a crime and have taken concrete action to advance this plot.^{[citation needed]}

• Administrative detention
• Arbitrary arrest and detention
• Mass arrest
• Pre-crime
• Preventive detention