A senior senator is now asking whether the Trump administration has been complying with federal law in implementing the partial government shutdown, now entering its fifth week.

Democratic Sen. Mark Warner, whose Virginia constituents include many federal employees in the national capital region, has sent a series of letters to key departments raising some doubts about whether President Donald Trump and his administration is in compliance with the Antideficiency Act.

The federal law, which dates back to 1982, is supposed to limit the federal government’s ability to spend money in the absence of appropriations from Congress. As more federal workers are being called back to work (still without pay) at agencies affected by the partial shutdown, it’s not clear if a uniform standard has been applied.

Warner cites examples in letters to each of the departments he has written: Agriculture, Interior, State, Transportation and Treasury. He also sent a separate letter to the IRS, which has been recalling employees to help process 2018 tax returns.

In a letter to Secretary of State Mike Pompeo, Warner cited as an example a conference for ambassadors and chiefs of mission that went on as scheduled just last week.

“In another example, on January 17, 2019, your department announced it was recalling all furloughed State Department and USAID employees in order to carry out the Department’s mission without providing additional background on how this complied with the Anti-Deficiency Act and why that move was needed to avoid imminent threats to human life or property,” the senator wrote.

Warner wrote that he did not see the broad expansion of activities conducted during the ongoing shutdown would comply with the Justice Department’s existing guidance on operations during a funding lapse.

In another of the letters, Warner asked Transportation Secretary Elaine L. Chao for her justification in bringing back furloughed Federal Aviation Administration employees for purposes other than activities that protect life and property.

“On January 15, 2019, more than three weeks after the shutdown began, under your supervision the Federal Aviation Administration (FAA) announced it was recalling furloughed inspectors and engineers to perform work such as air-safety checks, and routine activities such as approving new aircraft for commercial carriers’ fleets and new flight routes,” Warner wrote.

The partial government shutdown has reportedly held up the approval process for several new commercial routes, including the planned launch of Southwest Airlines service to Hawaii.

Warner asked the departments in question, and the IRS, if the Justice Department or the Office of Management and Budget has provided any specific guidance subsequent to the start of the shutdown in December.

The Government Accountability Office, which is part of the legislative branch, also plays a role in reviewing allegations of violations of federal appropriations law.

In early January, the GAO told Roll Call that it was offering “technical assistance” on legal compliance with the lapse in appropriations. The agency, “has also provided Congress with analysis related to government operations after a shutdown has concluded,” a GAO spokesman said.