First legal challenge

The new redistricting was initially challenged in Fletcher v. Lamone, a case brought by a number of African-American voters who believed that the new map diluted the strength of the African-American vote, violating the requirement of equal representation under Article One of the United States Constitution, equal protection granted by the 14th Amendment and equal voting rights from the 15th Amendment. They further challenged the No Representation Without Population Act, believing this further constituted a dilution of their vote. The case was heard by a three-judge panel at the District Court of Maryland in December 2011, and in a unanimous decision, the District Court found in favor of the state, issuing a summary judgement that asserted that the plaintiffs had not shown harm from the new district map nor from the Act.^[7] On appeal to the Supreme Court, the court issued a summary disposition that upheld the District Court's ruling.^[8][9]

Second legal challenge

A separate challenge arose from other residents of the state in 2013. Aware that the District Court of Maryland had ruled that the redistricting map was not considered partisan based on Fletcher v. Lamone, these citizens challenged the redistricting's use of "narrow ribbons and orifices" that were used to connect non-contiguous regions having a targeted population distribution in the state's 4th, 6th, 7th, and 8th districts.^[10] Of particular concern was the 6th district. Previously it had covered most of the rural northwestern part of the state along the Pennsylvania border and was a predominantly Republican district with a largely Caucasian population that had supported Representative Roscoe Bartlett for two decades. After redistricting, the 6th district still covered the western arm of the state, but now also included many of the suburban and metropolitan areas across the border from Washington D.C., thereby increasing the number of African-American voters within it. The number of registered Republicans dropped by 70,000 voters, roughly 20% of the registered voters in the district. As a result, Bartlett lost his seat to Democrat John Delaney in the 2012 elections by more than 20% of the vote.^[6] The complaint stated that because these majority Republican districts had been remapped to predominantly represent Democrats, the new district boundaries violated their rights of equal representation, the right to vote under the 14th Amendment, and the rights of association under the 1st Amendment.^[10]

The case, filed as Benisek v. Mack, was reviewed by Judge James K. Bredar who deemed that none of the complaints brought by the plaintiffs were actionable and denied the request for a standard three-judge hearing in April 2014. Judge Bredar did find that the case represented a substantially different subset of residents than Fletcher and rejected the defense's argument for res judicata. In response to the plaintiffs' arguments, Judge Bredar found that the plaintiffs did not provide an effective measure to demonstrate partisan gerrymandering as suggested by Vieth v. Jubelirer, thereby nullifying their Article One and 14th Amendment claims, and that the affected citizens still had their rights to participate in the political process intact, thus denying any relief based on the 1st Amendment claim.^[11] The plaintiffs appealed to the Fourth Circuit Appeals Court, but the appeal was summarily denied in October 2014 on the basis that their claims were insubstantial, as determined by Bredar.^[12] The plaintiffs issued a petition for writ of certiorari from the Supreme Court of the United States, arguing that because the District Courts are required to hear any substantial constitutional challenges to state redistricting under Section 2284 of Title 28, the Appeals Court's dismissal based on the "insubstantial" claim was inappropriate.^[13] The case, Shapiro v. McManus, was accepted by the Supreme Court in June 2015, with oral arguments heard in November 2015 and the decision issued in December 2015.^[14] The court unanimously agreed with the petitioners that the claims presented were not insubstantial, thus clearing the bar set by Goosby v. Osser, and ordered a full three-judge hearing of the case at the District Court; the court did not otherwise comment on the merits of the petitioners' complaints related to the redistricting.^[15][16]

Supreme Court

Seeking an expedited ruling, the plaintiffs filed a request for a jurisdictional statement to the Supreme Court on September 1, 2017, to reverse the District Court's denial of summary judgement and injunctions and placing the case on hold.^[20] While the Supreme Court declined to reverse the District Court's orders, the court did agree to hear the case on its merits on December 8, 2017.^[21]

Oral arguments were heard on March 28, 2018. In contrast to Gill v. Whitford, the justices seemed to indicate that the redistricting of Maryland's 6th district was a much more aggressive partisan gerrymandering than that in Wisconsin, but still debated whether they had a proper measure to evaluate partisan division, whether the court should be involved in that decision, and whether such matters are to be regulated through federal or state legislation.^[22]

The Court issued its per curiam decision affirming the Appeals' Court ruling on June 18, 2018, the same day that the Gill decision was announced. In the decision, the court did not address the merits of the gerrymandering case, but instead found that the District Court, in denying the issuing of an injunction on the use of the redistricting maps, had not engaged in an "abuse of discretion", given both the pending legal challenge of Gill and the need for "due regard for the public interest in orderly elections".^[23] The decision further argued that the plaintiffs had waited too long from the time that the redistricting maps were certified to file their case.^[24]

Supreme Court

Frosh petitioned the Supreme Court to hear the new challenge of whether the District Court could make its summary judgement, and the court agreed in early January 2019 to hear the case. This new case was heard as Lamone v. Benisek (Docket 18-726)^[27] alongside Rucho v. Common Cause, another partisan gerrymandering case from North Carolina.^[28] The case was decided on June 27, 2019; a 5–4 majority determined that claims of partisan gerrymandering present a nonjusticiable political question that could not be handled by the federal court system. Along with Rucho, the Supreme Court vacated the District Court's judgement and remanded the case to that court, effectively leaving the existing redistricting maps in place.