The Ninth U.S. Circuit Court of Appeals ruled Tuesday that veterans involved in the infamous Pentagon mustard gas experiments were entitled to disability and death benefits, as well as information regarding the chemicals used and their effects on health. This marks the end of an uphill battle that has raged since the 1990s.

From 1955-1975, roughy 60,000 WWII veterans and servicemen were exposed to mustard gas and a chemical weapon called Lewisite during a series of classified experiments administrated by the CIA and Army. The operation remained secret until declassified documents related to the study surfaced in the early 1990s.

Both mustard gas and Lewisite are chemical weapons that act as blister agents and lung irritants. During the experiments, servicemen were exposed to these chemicals to test the effectiveness of gas masks and hazard suits. Most veterans did not volunteer for the study. The injuries soldiers sustained during these tests followed them for their entire lives, but the government and Department of Veterans Affairs point-blank refused to provide medical assistance.

The tides changed in 2009 when a lawsuit alleged that the government denied 97 to 99 percent of the servicemen involved in these experiments their disability and death benefits. After much litigation, the court found that the government’s responsibility to these test subjects did not conclude with the experiments in 1975, and it must provide restitution to those harmed in the program.