As a former state attorney general, Senator Kamala D. Harris, the Democratic nominee for vice president, has received significant scrutiny of her record on law enforcement, facing questions and criticism about uneven prosecutions of killings by police officers.
But she is less known for another role she took on, opposing the consolidation of institutions in the health care industry, which has become a major force driving the cost of medical care higher for consumers. She challenged proposed mergers between industry behemoths and anti-competitive behavior by powerful hospital systems and drug makers.