Senior Justice Department lawyers advised acting attorney general Matthew G. Whitaker not to sign a gun regulation change earlier this week, warning him that doing so could lead to a successful legal challenge to his appointment as the nation’s top law enforcement official, according to officials familiar with the discussions.

The internal debate over Whitaker’s signature, which began weeks ago, shows how concerned even top Justice Department executives are that his appointment to acting attorney general is vulnerable to a legal challenge, particularly when lawyers suing the department over various policy issues need to find only one federal judge who agrees with that position, according to officials familiar with the discussions. They spoke on the condition of anonymity to detail internal discussions.

The litigation concerns surrounding Whitaker are partly fueled by anxiety inside the Justice Department about judicial activism, most often reflected in what some lawyers call the “national injunction” problem — that when lawyers challenge a particular government policy in court, a lone U.S. District Court judge has the authority to issue a court order blocking that policy across the entire country. Judges have issued such injunctions against Obama administration policies and Trump administration policies, but most of the criticism of national injunctions comes from conservative lawyers, who say lower court judges should not have such an outsized impact on federal government decisions.

The concern expressed by senior Justice Department officials who did not want Whitaker to sign the bump-stock ban was that by doing so, it presented a litigation risk to him and the department; a judge considering legal challenges to the ban could also be asked to rule on whether Whitaker was legally appointed as attorney general. If a judge ruled against him, Whitaker would be in the unfortunate position of having a federal judge declare he wasn’t really the attorney general, these people reasoned.

The discussions took place off and on over about two weeks, and ultimately Whitaker sided with the lawyers who said he could sign the regulation. Even if a judge ruled against him, officials said, another Justice Department official could immediately re-sign it and avoid a significant delay in the ban on bump stocks.

The day the ban was announced by the Justice Department, a handful of gun-rights groups said they would challenge it in court, and attack Whitaker’s authority to implement such a change. Their lawsuit filed in federal court in Washington, D.C., refers to Whitaker as “the purported acting attorney general.”

The suit contends Whitaker “is unable to lawfully perform the duties and responsibilities of attorney general, including the execution on December 18, 2018 and implementation of the final rule.”

This should be interesting.