The largest federal employee union is suing the Trump administration over the ongoing partial government shutdown.

The American Federation of Government Employees and Washington-based employment law firm Kalijarvi, Chuzi, Newman & Fitch filed their legal action in the U.S. Court of Federal Claims on Monday on behalf of its members and any federal employees working without pay.

“Our members put their lives on the line to keep our country safe,” AFGE president J. David Cox Sr. said in a statement. “Requiring them to work without pay is nothing short of inhumane. Positions that are considered ‘essential’ during a government shutdown are some of the most dangerous jobs in the federal government. They are frontline public safety positions, including many in law enforcement, among other critical roles. A substantial number of those working without pay are military veterans.”

About 420,000 of the 800,000 federal employees affected by the Dec. 22 shutdown are working without remuneration, though they will likely receive back pay. The shutdown, now in its 10th day, was triggered by a breakdown in negotiations between the White House, Republican lawmakers, and congressional Democrats over border wall funding. President Trump wants $5 billion for border security, while Democrats are only prepared to give him $1.3 billion.

Kalijarvi, Chuzi, Newman & Fitch previously sued the administration on behalf of 25,000 workers over the 16-day shutdown in 2013 using the Fair Labor Standards Act, the AFGE said. The act requires the government to pay employees on time. The U.S. Court of Federal Claims found last year that the impacted workers were entitled to twice their back pay.