A consistent liberal vote on the Supreme Court with an unflappable belief in the US system of government and a pragmatic view of the law, Breyer has sought to focus the law on how it could work for the average citizen. He was no firebrand and was quick to say that the Supreme Court couldn’t solve all of society’s problems. He often stressed that the court shouldn’t be seen as part of the political branches but recognized that certain opinions could be unpopular.

In his later years on the court, he was best known for a dissent he wrote in 2015 in a case concerning execution by lethal injection. He took the opportunity to write separately and suggest to the court that it take up the constitutionality of the death penalty.

In the opinion, Breyer wrote that after spending many years on the court reviewing countless death penalty cases, he had come to question whether innocent people had been executed. He also feared that the penalty was being applied arbitrarily across the country. He noted that, in some cases, death row inmates could spend years — sometimes in solitary confinement — waiting for their executions.

This story has been updated with additional details and background information.