UPDATE (Sept. 24, 2018, 2:16 p.m.): Axios reported Monday morning that Deputy Attorney General Rod Rosenstein had resigned to White House Chief of Staff John Kelly. But Rosenstein has remained in his position — at least for now. The White House issued a statement saying that President Trump will meet with Rosenstein on Thursday. In May, we published this article discussing what Trump’s hypothetical firing of Rosenstein could mean for Robert Mueller’s probe into interference in the 2016 U.S. election.

President Trump has never had a particularly friendly attitude toward the Department of Justice. But his attacks on the nation’s chief law enforcement agency have escalated in recent months, culminating in a demand — by tweet — for an investigation into whether the FBI engaged in politically motivated surveillance of his 2016 presidential campaign. Deputy Attorney General Rod Rosenstein quickly assented (sort of), to the dismay of critics who say that Trump is trying to weaken the department’s historic independence in an attempt to interfere with special counsel Robert Mueller’s Russia investigation. Some even speculated that the order could strengthen the obstruction of justice case against Trump — especially if he uses it as a pretext to fire Rosenstein, who is overseeing Mueller’s probe and has been the subject of veiled threats from the president for months.

What would happen if Trump were to give Rosenstein the boot? Dismissing him would be a more obvious attempt to control the outcome of Mueller’s investigation than insisting on a separate probe of the FBI. But even in the case of a hypothetical Rosenstein firing, there isn’t a clear line between the president’s legitimate authority over law enforcement agencies and criminal interference in an ongoing investigation. Dismissing the deputy attorney general would be a political bombshell, but the extent of the legal fallout would depend largely on what the president did next.

The specter of obstruction of justice has been hanging over Trump’s interactions with the Department of Justice since last year, when Rosenstein appointed Mueller to investigate interference in the 2016 election. In addition to exploring the possibility that Trump’s campaign was involved in the Russians’ meddling, Mueller has reportedly been looking into whether the president interfered with the probe, most notably by firing FBI Director James Comey last May.

Unlike with Comey, though, Trump does not have the legal authority to dismiss Mueller directly, according to most legal experts (and despite the White House’s assertion to the contrary). Thanks to Attorney General Jeff Sessions’s recusal from the Russia investigation, Rosenstein is the one person who can fire Mueller. But Rosenstein needs a reason to do so, such as misconduct or a conflict of interest, and he has signaled that he sees no such justification.

Trump does have the authority to fire members of his administration, including Rosenstein. In some sense, dismissing Rosenstein could be seen as just the latest in a series of attention-grabbing terminations of senior administration officials. The firing might be politically unwise, but it wouldn’t be legally suspect.

Trump could add fuel to the obstruction of justice fire, though, if he subsequently used Rosenstein’s ouster to intimidate Mueller or attempt to influence the Russia investigation, according to legal experts. There are several ways this could play out. One is that Trump might pressure Rosenstein’s replacement to curtail the Russia investigation. (Solicitor General Noel Francisco is next in line at the Justice Department.) Trump could tell Francisco, for example, to stop Mueller from pursuing any avenue of inquiry that involves Trump’s financial records or other sensitive topics, or he could order him to fire Mueller and either allow the investigation to continue with a replacement (or without a special counsel at all) or shut it down entirely.

If that’s not something Francisco is willing to do, Trump could try another tack: appointing an acting deputy attorney general who would fill the vacancy created by Rosenstein’s removal. But this could spark a legal showdown, since it’s not clear whether this person would actually be in charge of the Russia investigation until being confirmed by the Senate. Trump could theoretically move someone previously confirmed by the Senate into Rosenstein’s position until a permanent replacement could be confirmed, but this would also likely end up in court because the law that allows this intra-agency reshuffling may not apply to people the president has fired.

But simply firing Rosenstein may not mean obstruction. Paul Rosenzweig, a former prosecutor and professor at George Washington University Law School, said Trump’s profligate firing habits could help immunize him against the allegation that he’s trying to foil the Russia investigation. “You could say that this strengthens the obstruction case against Trump because he appears to fire people when they get too close to him or his friends in this investigation,” Rosenzweig said. “But you can also argue that Trump has gotten rid of dozens of people in his administration at this point, and the pattern isn’t obstruction of justice — it’s that he fires people who piss him off.”

Rosenzweig added, though, that even if Rosenstein’s firing is a prelude to ending Mueller’s investigation, the probe could be harder to stop than Trump anticipates. The raid in April on the office of presidential lawyer and fixer Michael Cohen was conducted by prosecutors from the U.S. Attorney’s Office for the Southern District of New York, rather than Mueller’s investigators, and Mueller also worked with former New York Attorney General Eric Schneiderman on the case against former Trump campaign chairman Paul Manafort, which means that these lines of inquiry — and perhaps others — could be continued without Mueller.

Whatever Trump’s intention, it’s unlikely that ousting Rosenstein would make it easier for Trump to rein in the investigations surrounding him. And if the firing appears to have been motivated by a desire to impede the investigation, it could end up multiplying the president’s legal troubles.