Why Congress Can’t Stop the CIA From Working With Forces That Commit Abuses

For more than two decades, the U.S. military has been barred from providing training and equipment to foreign security forces that commit “gross violations of internationally recognized human rights.”

The law, named for its author, Vermont Sen. Patrick Leahy, applies to military assistance for foreign units funded through the Defense or State departments. Lawmakers including Leahy, a Democrat, acknowledged that it does not cover commando outfits like Afghanistan’s Zero Units.

In an email, Leahy said he believes that the law’s human rights requirements need to be expanded to “cover certain counter-terrorism...