The U.S. Department of Justice says it is planning to file a lawsuit against Washington state over the state’s new law aimed at covering occupational diseases such as cancer under presumption for those who worked at the Hanford nuclear site in Hanford, Washington.

In a letter to Washington Gov. Jay Inslee dated Oct. 31 but widely circulated Wednesday, the Justice Department is calling H.B. 1723, signed into law in March, unconstitutional in that it violates the Supremacy Clause of the U.S. Constitution because “it discriminates against the federal government and those whom it deals” and “through such limited application” the law “purports to directly regulate the (f)ederal (g)overnment.”

H.B. 1723 addresses a number of illnesses, including various cancers, suffered by workers of the 560-square-mile federally operated and decommissioned nuclear site, which has gone by several names since it opened in 1943 during World War II. Hanford workers helped manufacture the plutonium used in one of the atomic bombs dropped on Japan in 1945.

The law, which went into effect on June 7, establishes presumption under the state’s workers compensation laws for workers who suffer from heart problems, neurological diseases, respiratory illnesses and specific cancers, including leukemia, lung cancer, bone cancer, kidney cancer, lymphoma and other cancers affecting more than a dozen body parts, according to the latest draft.

The Justice Department, which is not commenting on the letter, says it is “willing to give the State of Washington the opportunity to resolve this matter without litigation” and is giving the governor until Friday to respond.

The governor’s office said it would like to work with the federal government, according to an emailed statement from a spokeswoman.

“Our state has reached out to the Department of Justice to discuss their concerns. Our priority remains ensuring Hanford workers have access to the care and compensation they deserve. It’s the right thing to do,” the spokeswoman wrote Wednesday morning.