On October 24, 2019, Governor John Carney announced the nomination of Montgomery-Reeves to be a justice of the Delaware Supreme Court, to fill the vacancy left by the elevation of Collins J. Seitz Jr. to Chief Justice.[7] On November 7, 2019, her nomination was confirmed by the Delaware Senate. She was the first African-American justice on that court.[11] She was sworn into office on January 3, 2020.[12] In 2021, Montgomery-Reeves wrote the majority opinion holding that Senate records submitted to the University of Delaware archives by President Biden were not subject to demands under the Delaware Freedom of Information Act.[13] Her service as a justice of the Delaware Supreme Court ended on February 7, 2023, when she was elevated to the United States Court of Appeals for the Third Circuit.[14]
During her confirmation hearing, Republican senators questioned Montgomery-Reeves about a strategic plan to increase diversity in Delaware's judiciary. The plan was based on recommendations made by the Delaware Supreme Court's Diversity Strategic Planning Steering Committee, which Montgomery-Reeves had co-chaired. She was asked about a recommendation that prospective lawyers be able to use clerkships and recommendations in lieu of passing the bar exam, which the committee said was a barrier to minority people. The committee also recommended that portraits of white judges and justices be removed from courthouses as a way to "reduce implicit bias and identity threat in the court environment." Montgomery-Reeves distanced herself from these recommendations by saying that she had neither written nor edited any of them despite being committee co-chair.[19] On September 28, 2022, her nomination was reported out of committee by a 13–9 vote.[20] On December 8, 2022, the United States Senate invoked cloture on her nomination by a 57–39 vote.[21] On December 12, 2022, her nomination was confirmed by a 53–35 vote.[22] She received her judicial commission on February 7, 2023.[14]
