Senator Kamala Harris (D-Calif.) announced a proposal that would address the gender wage gap in the United States. The Democratic presidential hopeful’s plan would require large companies to periodically obtain certification of equal pay. The plan would require companies with 100 or more employees to get an “equal pay certification” within two years of Harris’ inauguration to prove that men and women are paid equally for equal work. Companies that fail to get the certification would be fined 1 percent of their profits for every 1 percent wage gap, according to...