Legal challenges to the appointment of acting Attorney General Matthew Whitaker have been piling up.

President Donald Trump selected Whitaker as the temporary replacement for Attorney General Jeff Sessions, who resigned at the president’s request in November. It was a strange choice for a few reasons.

Whitaker served as Sessions’s chief of staff, which means Trump handpicked him for the role, rather than leaving Rod Rosenstein, the deputy attorney general and No. 2 at the Department of Justice, in charge.

Whitaker was also an odd choice for another reason: Prior to joining the administration, he had been a vocal and unabashed critic of special counsel Robert Mueller’s investigation into Russian interference in the 2016 presidential election.

This had led some calls, mostly from Democrats, that Whitaker recuse himself from the probe, which he now oversees. But these lawsuits are challenging Whitaker’s appointment as a matter of law, not ethics.

Trump made his decision to name Whitaker acting attorney general based on a provision in the Federal Vacancies Reform Act of 1998 (FVRA), which lays out a few categories of officials who can serve in executive branch roles if a vacancy opens up. Whitaker qualifies because he’s worked in the Justice Department for 90 consecutive days and is a high-level earner on the government pay scale.

But some legal scholars argue that Whitaker’s appointment is unconstitutional because he never received Senate confirmation, and other Senate-confirmed officers were available to fill the interim role.

They’re also making the argument that the Justice Department’s order of succession should trump the Vacancies Reform Act, meaning Rosenstein should have been tapped to lead until a suitable replacement was nominated and Senate-confirmed.

The Justice Department’s Office of Legal Counsel issued an opinion last week that defended Whitaker’s appointment as legal. But that’s unlikely to quell the numerous legal challenges.

Here’s what you need to know about some of the cases brought so far. We’ll update as events develop.

Senate Democrats are suing to block Whitaker

The case: Blumenthal v. Whitaker

Who’s bringing it: Government watchdog groups filed the lawsuit on behalf of Senate Democrats in DC federal district court. Senate Judiciary Committee members Richard Blumenthal (D-CT), Sheldon Whitehouse (D-RI), and Mazie Hirono (D-HI) are the lead plaintiffs.

What the case is about: Senate Democrats want to block Whitaker from serving as acting AG, arguing that his appointment violates the Constitution because he lacks Senate confirmation. Even though the role is temporary, they say, it tramples on the Appointments Clause, which gives the Senate the “advice and consent power” over “principal officers” — high-level Cabinet positions, of which the attorney general is definitely one.

Senators say there are legitimate questions about Whitaker’s background, from his comments about special counsel Robert Mueller to his sketchy business dealings to his pretty thin legal résumé. This would make for a contentious Senate confirmation in normal circumstances, but Whitaker, as acting AG, doesn’t have to face lawmakers’ scrutiny while still being empowered to carry out all the duties of the nation’s chief law enforcement officer.

“If allowed to stand,” Senate Democrats argue in their lawsuit, “Mr. Whitaker’s appointment would create a road map for the evasion of the constitutionally prescribed Senate advice-and-consent role.”

Read it here.

Maryland fights a health care case — and Whitaker’s appointment

The case: Maryland v. US

Who’s bringing it: Maryland’s Attorney General Brian E. Frosh. The case is currently in federal district court in Maryland. Fifteen other state attorney generals filed a friend-of-the-court brief on November 26 in support of Maryland’s arguments.

What the case is about: Maryland is suing the Justice Department over its decision to stop defending protections for people with preexisting conditions under the Affordable Care Act. The suit originally named former Attorney General Sessions, but now Maryland is asking the courts to block Whitaker and recognize Rosenstein, the deputy AG, as the rightful acting AG.

“The Constitution and Congress have established vitally important processes for filling high-level vacancies in the federal government,” Frosh said in a statement. “Few positions are more critical than that of US Attorney General, an office that wields enormous enforcement power and authority over the lives of all Americans.”

Maryland’s motion argues that Whitaker’s appointment violates the federal statute that governs the attorney general order of succession, which would have put Rosenstein in charge. (Justice Department lawyers have said the Vacancies Reform Act can be used in lieu of the succession order.)

The case also argues that Whitaker’s appointment, though temporary, is unconstitutional because he hasn’t faced Senate confirmation and is serving as a “principal officer.”

The Justice Department has asked a judge to dismiss the case, and a hearing is scheduled for December 19.

Read it here, and read the AG’s amicus brief in support here.

A gun rights case

The case: Michaels v. Whitaker

Who’s bringing it: Barry Michaels, a Nevada man convicted of securities fraud. He’s asking the Supreme Court to rule on the constitutionality of a firearms ban for felons.

What the case is about: Michaels is challenging a federal law that bars felons from possessing firearms. Attorneys last week filed a motion to replace Sessions’s name, which had previously been on the suit, with Whitaker’s. This is usually a noncontroversial process, but Michaels’s attorneys made it so by saying that since there were so many questions about the legitimacy of Whitaker’s appointment, the court should resolve the issue.

The motion takes up the same argument as the Maryland lawsuit (the attorneys behind the motion joined the Maryland case, too): that the federal statute governing the AG order of succession should trump the Vacancies Reform Act, and even if it doesn’t, the Appointments Clause prevents a non-Senate-confirmed person from exercising the functions of a principal officer, even if it’s temporary.

As University of Texas law professor Steve Vladeck noted at SCOTUSblog, the plaintiffs acknowledge that this case hasn’t been taken up by lower courts yet but are arguing that there’s “significant national interest in avoiding” controversy over who’s allowed to serve as acting attorney general.

There’s also an interesting update to this case: On Monday, an amicus brief was filed to the Supreme Court on behalf of Mort Rosenberg, who is described in the brief as the “leading authority” on the Federal Vacancies Reform Act and “intimately involved” in its enactment during his time as an analyst on the Congressional Research Service.

Rosenberg argues that Rosenstein is the rightful acting AG because Congress established a Justice Department order of succession, and the administration is incorrect when it says it can sidestep that and use the Vacancies Act instead. The “Vacancies Reform Act did nothing to break Congress’s 150-year practice regarding the succession of the Attorney General,” the brief states.

This doesn’t take up the question of whether Whitaker needs to be Senate-confirmed; instead, it’s giving the historical and political context for why the attorney general should be — and was intended to be — treated differently than other executive branch roles.

Read the case here and the amicus brief here.

A Texas business leader finds a creative way to fight an indictment

The case: US v. William Douglas Haning

Who’s bringing it: Douglas Haning, a Texas business executive who’s facing federal charges for putting substandard ingredients in pet food. The motion was filed in US federal district court in the Eastern District of Missouri.

What the case is about: Lawyers for Haning filed a motion that challenges the constitutionality of Whitaker’s acting appointment. Former AG Sessions had been involved because a US attorney had to recuse himself from the case, according to Politico. With Sessions out, Whitaker steps in.

“For a federal criminal prosecution, the rule of law is profoundly important and the Department of Justice in this case is not upholding the rule of law,” Justin Gelfand, one of Haning’s lawyers, told Politico. “As a matter of federal law, the attorney general is in charge of this prosecution, but the office of attorney general is currently staffed by someone appointed in violation of Article II of the Constitution.”

This case has taken a couple of twists and turns since Haning’s attorneys first filed the motion. First, the government responded, defending Whitaker’s appointment. Government prosecutors later filed a superseding indictment — a new indictment that replaces the original — but excluded the name or title of the acting attorney general or any other US attorney, and only included the prosecutors who are actually trying the case. The original indictment had included then-AG Sessions’s name, according to the motion.

The omission of the acting AG’s name or title doesn’t eliminate the question of Whitaker’s legitimacy — and actually raises new questions, Gelfand, Haning’s attorney, told me. His team has filed another motion to dismiss the superseding indictment, once again arguing that Whitaker’s appointment is unlawful and unconstitutional.

Read it here.

And another Texan fights one too

The case: US v. Luis Valencia

Who’s bringing it: A defendant who is charged with being part of a group of workers that stole oil from energy companies.

What the case is about: Attorneys are arguing that the case against this defendant should be dismissed because Whitaker is an unlawful acting attorney general. Valencia is being prosecuted in the Western District of Texas, but attorneys for the defendant argued Whitaker didn’t have to be directly involved in the case for his appointment to affect the prosecution.

A federal judge heard arguments on the case on November 26, and ruled November 27, denying the motion to dismiss the case. The judge ruled that Whitaker’s appointment was lawful under both the Federal Reform Vacancies Act and the Appointments Clause. According to the Associated Press, the judge added that even if there were questions about whether Trump could skip the DOJ line of succession, the actual charges against Valencia could move forward because there are others at the DOJ with the power to prosecute the case.

Attorneys for Valencia are appealing the case, so it’s not quite over yet.

Read it here.

An asylum ban challenge takes on Whitaker

The case: O.A. v. Trump

Who’s bringing it: Six asylum seekers, including three kids, who are challenging Trump’s asylum ban. (O.A. represents just one of the plaintiffs.)

What the case is about: On November 10, Trump issued an executive order barring people from seeking asylum if they cross the border illegally and outside a designated port of entry. Immigration advocates have challenged the ban, and a judge temporarily put the order on hold.

This latest case, filed in federal district court in DC, not only seeks to challenge Trump’s order but also argues that Whitaker doesn’t have the power to issue the regulations because his appointment is invalid, as it violates the federal succession statute and the Appointments Clause. One of the problems with these Whitaker motions is the challenge of standing: basically, the need to prove harm from a particular action. This asylum ban case may be one of the stronger examples of that.

A hearing is scheduled for December 17.

Read it here.

A case argues immigration judges’ rulings are invalid, because Whitaker

The case: Rojo-Ramirez v. Trump

Who’s bringing it: Carlos Rojo-Ramirez is facing deportation proceedings in Colorado who has filed a lawsuit in the US District Court for the District of Colorado.

What the case is about: Rojo-Ramirez is challenging the authority of an immigration judge to preside over his removal proceedings. Attorneys for Rojo-Ramirez argue that Whitaker’s appointment violates the Appointments Clause, the Department of Justice succession statute, and the Federal Vacancies Reform Act, which they say is being improperly applied.

The problems with Whitaker’s appointment trickle down to immigration judges, the attorneys argue, because an unlawful attorney general can’t preside over or delegate power to immigration judges — a chain of authority the plaintiffs say is clearly defined by statute and federal regulations.

Read it here.

A question about asylum

The case: Matter of Daniel Girmai Negusie

Who’s bringing it: Immigration advocates are challenging Whitaker’s ability to review and decide immigration cases.

What the case is about: An asylum-seeker from Eritrea was denied asylum because he served as a guard in a prison camp, though he alleged he was conscripted and would face persecution if he returned. The question deals with whether someone who participated in alleged wrongdoing in their home country is still eligible for asylum if they can show they were forced to participate.

The case had been argued before the Supreme Court and the Board of Immigration Appeals (BIA), the highest-level court that rules on immigration cases. The BIA ruled that yes, exceptions can be made for people acting under duress, although it decided this case didn’t meet that threshold.

But then-Attorney General Jeff Sessions referred the case to himself, something he has the authority to do as AG, so he could issue a decision as to whether there should be an exception for persecutors who are coerced. Sessions didn’t get a chance to issue a decision before he departed — and now immigration group says Whitaker doesn’t have the authority to review the case.

“Implicit in the authority granted to the attorney general over immigration cases is the legality of his or her appointment,” said Trina Realmuto, directing attorney at the American Immigration Council, in a statement. “The improper appointment of the acting attorney general not only is unlawful, but undermines the rule of law that the head of the Justice Department is obligated to uphold.”

Read it here.

A Trump travel-ban waiver challenge

The case: Alharbi et al v. Miller et al

Who’s bringing it: Yemenis who were approved to get US visas, but never received them since Trump’s travel ban went into effect. The case is being heard in the US District Court in the Eastern District of New York.

What the case is about: Trump’s travel ban was upheld by the Supreme Court, but this case focuses on waivers for the travel ban. Many of the documents in this case aren’t public, but lawyers have filed a challenge to Whitaker’s appointment.

And the most meta: a Mueller challenge

The case: Andrew Miller v. United States

Who’s bringing it: The court asked about Whitaker in a case involving Andrew Miller, an associate of conservative political operative and Trump confidant Roger Stone, who’s under the scrutiny of special counsel Robert Mueller. Miller, who’s represented by attorneys from a conservative nonprofit group, is challenging a grand jury subpoena. A US district court judge ruled against Miller, and now the US Court of Appeals for the District of Columbia is taking up the question.

What the case is about: This case, which predates Whitaker, is about the validity of the special counsel. Miller has been trying to quash a grand jury subpoena, and he’s fighting it by saying that Mueller’s appointment is unconstitutional because — wait for it — he hasn’t gotten Senate confirmation. (This, if you’ve looked at the president’s Twitter feed, is an argument he likes.)

Mueller was appointed by Rosenstein under a Department of Justice regulation, but Miller is arguing that the special counsel’s powers mean he should be designated a “principal officer.”

A conservative legal scholar put forward this stance earlier this year, though so far it hasn’t gotten any traction in the courts. A Trump-appointed judge also shot down a similar argument brought by the Russian firm indicted for funding the troll factory that spread misinformation leading up to the 2016 election.

Attorneys argued Miller’s case in front of the DC Court of Appeals weeks ago, but the judges asked lawyers on both sides to address what effect, if any, Whitaker’s appointment has on their cases. Both Miller’s lawyers and the government came back and said it’s not an issue at all.

The case, however, highlights the tricky nature of these constitutional questions. The issue of Senate confirmation, specifically, is being used by both those who want to protect and those who want to sideline the Mueller probe.

Read it here; read Miller’s response here and the government’s response here.