On Aug. 1, Gov. Charlie Baker signed into law a measure to help close the gender wage gap. The enacted bill, sponsored by Sen. Patricia Jehlen, D-Somerville, and Rep. Jay Livingstone, D-Boston, prohibits discrimination on the basis of gender in the payment of wages for comparable work unless the variation is based upon an approved mitigating factor, such as seniority or merit.The new law updates the Massachusetts Equal Pay Act, passed just after World War II.