Called to the Bar in 1987, Starmer entered the legal profession during a time of significant social change. He joined Doughty Street Chambers, a firm known for its commitment to human rights and civil liberties. As a young barrister, he did not just take cases to earn a living; he took them to fight for those who had been marginalized by the state or powerful entities. He earned a reputation as a meticulous and formidable advocate. Whether representing protesters or individuals challenging government decisions, his courtroom style was defined by calm authority and an unwavering focus on the facts. He was often sought out for his ability to synthesize complex information into clear, persuasive arguments.