WASHINGTON—Justice Clarence Thomas on Monday ended a decadelong silence during Supreme Court oral arguments, asking several questions in a case about domestic violence and firearm possession.

Justice Thomas’s questions, which voiced concern about protecting gun ownership rights, underscored yet another way the court has changed suddenly since the Feb. 13 death of Justice Antonin Scalia. Justice Scalia was a leading figure during oral arguments, often &mod=article_inline" class="icon none" >dominating the questioning of lawyers...