Connecticut Gov. Dannel Malloy (D) signed a ban on employer salary history inquiries into law, meant to help close the pay gap between men and women.

An Act Concerning Pay Equity (Public Act No. 18-8) prohibits employers and third parties like recruiting firms from asking about a worker’s salary history. Also under the new law, employers can’t forbid workers from discussing their salaries or discipline them for doing so. Employers also may not require workers to sign documents that would keep them from asking about salaries.

In Connecticut, women are paid 82 cents on average for every dollar...