Let’s start with a few modest propositions:

Law enforcement officials must play it scrupulously down the middle.

It is extraordinarily dangerous for those with enormous investigative and prosecutorial power to use it to settle scores or punish opponents.

Facts and law must drive an investigation to its logical conclusion, rather than preconceived notions and political biases.

Perceptions matter. A lot. It is important for the legitimacy of law enforcement that its work not just be apolitical but that it also appear apolitical.

Simple enough, right? These are among the principles that all good prosecutors abide. They are the reason many people rightly have concerns about Matt Whitaker’s service as acting attorney general of the United States. For the same reason, they also raise concerns about New York’s incoming state attorney general, Letitia James.

Whitaker has been forcefully criticized for remarks he made—as a private citizen—disparaging Bob Mueller’s investigation of Russian election interference. But Whitaker was only forcefully criticized for those remarks when he became the acting attorney general.

Here is a selection of comments attributable to private citizen Whitaker, drawn from a Politico article, demonstrating that Whitaker arguably prejudged the scope and the merits of the investigation he now leads:

“The truth is there was no collusion with the Russians and the Trump campaign.”

“If Bob Mueller … does go beyond the 2016 election and get into Trump Organization finances, unrelated to the 2016 election and really unrelated to Russia coordination, if it even exists, I think that would be crossing a red line and I think that’s when the deputy attorney general … needs to step in and pull the reins back on Bob Mueller if he starts to go outside the bounds of his delegation of authority.”

“If [Mueller] were to continue to investigate the financial relationships without a broadened scope in his appointment, then this would raise serious concerns that the special counsel’s investigation was a mere witch hunt….”

“I think fundamentally this investigation by Bob Mueller needs to be limited, it has to be limited and anybody who is saying that Bob Mueller looking into unrelated financial transactions of the president, his family or his associates before he seeks to get an extension of his authority is really trying to shred the Fourth Amendment."

Though I strongly disagree with Whitaker’s sentiments, it was perfectly acceptable for him to express them—as a private citizen. When he was named acting attorney general and became responsible for overseeing the Mueller probe, however, it was time for him to own what he said and recuse himself from the investigation. At the very least, his comments evinced an appearance of a conflict of interest. Remember, perceptions matter. A lot.

A recent letter released by the Department of Justice—meant to assuage critics of the acting attorney general’s refusal to step aside—actually undermined Whitaker’s argument that he could properly remain involved in, and in charge of, that investigation.

A Justice Department political appointee wrote that career officials who advised Whitaker on the conflict issue determined that his recusal was not mandatory but that it was advisable:

Acting Attorney General Whitaker had made public comments prior to his rejoining the Department that could … raise an appearance-of-impartiality issue …. Under an appearance of impartiality analysis, the ethics rules do not require a formal recommendation from the ethics officials. In a meeting with the Acting Attorney General’s senior staff, the … ethics official explained that ethics officials had not identified any prior precedents in which the Attorney General or other senior Department official had recused from a matter based upon statements made in the media prior to joining the Department. The ethics officials concluded, however, that if a recommendation were sought, they would advise that the Acting Attorney General should recuse himself from supervision of the Special Counsel investigation because it was their view that a reasonable person with knowledge of the relevant facts likely would question the impartiality of the Acting Attorney General (emphasis added).

This, ironically, was the letter arguing that Whitaker could properly remain in charge of the Mueller investigation.

According to the letter, even if Whitaker did not have an “actual” conflict of interest pursuant to Justice Department regulations, the appearance of a conflict was a compelling reason for him to step aside, at least in the view of career ethics officials. If he had sought their recommendation, which he conspicuously did not, ethics officials would have advised recusal. They know that an appearance of a conflict is a serious matter and, alone, is grounds to step aside. This is particularly true for someone who runs a law enforcement agency and leads that agency’s highest-profile criminal and counterintelligence investigation in decades.

When I served as a federal prosecutor, we spoke about “the line,” meaning the ethics line. And we said when a question arose, “If you can see the line, you are too close to it.” It’s actually an easy rule to apply and to follow. When it comes to recusal: If in doubt, recuse.

This maxim—don’t get close to the line—should never depend on who is in charge or who is the target of an investigation. It should apply equally to all prosecutors, at all times, in all cases.

Recently, voters in New York State elected Letitia James as the state’s attorney general—a momentous election that brought to one of the most powerful state law enforcement offices in the nation a highly accomplished woman of color. That’s good news, in part because it adds an important voice—hers—to that crucial function.

James’s office has jurisdiction and venue over numerous important investigations, financial and otherwise, into the Trump Organization, the Trump Foundation and members of the Trump family. Moreover, the work of the New York State Attorney General is beyond the pardon power of President Trump. That makes James’s role both incredibly important and incredibly sensitive. As a consequence, what she says and does—and what she has already said and done—will be intensely scrutinized. Is that fair? Sure. It comes with the territory that she volunteered to traverse.

What’s sauce for the goose is sauce for the gander. So let’s use the same standards applied to Whitaker and his statements about matters he came to supervise to James and her statements about matters she will come to supervise.

Here are some of the things that James said to the New York Times, all prior to taking office (that is, as a private citizen) and before she could have genuinely known the facts of the cases she has inherited:

Trump is an “illegitimate president.”

James’s decision to run for attorney general was largely “about that man in the White House who can’t go a day without threatening our fundamental rights.”

Trump could be charged with obstruction of justice, and she implied that foreign governments channeled money to Mr. Trump’s family’s real estate holdings, which she characterized as a “pattern and practice of money laundering.”

The Times further noted a statement released by James during her campaign declaring that, “Donald Trump’s days of defrauding Americans are coming to an end.”

Following her victory, James also told NBC News that:

She plans to launch sweeping investigations into President Donald Trump, his family and "anyone" in his circle who may have violated the law once she settles into her new job.

"We will use every area of the law to investigate President Trump and his business transactions and that of his family as well."

Mueller's "doing an excellent job." "I think he's closing in on this president and his days are going to be coming to an end shortly."

These are only comments to two news outlets retrieved in a brief search.

James’s comments—like Whitaker’s—were made before she took office and demonstrate a prejudgment of the facts and a political predisposition to the issues she now must manage apolitically and dispassionately. Every good prosecutor knows those comments are a problem.

Appearances matter—a lot.

To be sure, James, unlike Whitaker, was a candidate for elected office—so she had reason to say something during the campaign about the role she sought. But promising a specific outcome (we are going to launch sweeping investigations of a particular person) is materially different from promising a particular process (we are going to hold people accountable, apply the law and facts and follow the evidence wherever it leads). What’s more, most of the statements by James that I have noted here were made after she was elected, and these are both more telling than statements made in the heat of a campaign and require a higher level of circumspection. For instance, James’s comments to NBC News were made after her election but before she assumed office.

So, what should James do?

She could follow Whitaker’s lead, consulting with career ethics officials and then, as Whitaker did, ignoring them. But that doesn’t seem like a sound path. Why would anyone ask the most experienced people in the room what should be done and then not do it? Were the career officials wrong or did Whitaker just not like their advice? To pose this question is to suggest its answer.

In the alternative, James could consult with career ethics officials and then abide by their recommendations. That seems inarguably prudent.

Another path would be to recuse herself from investigations into the president’s family and family-run entities based on the appearance issue alone. But this might be a bridge too far. After all, the acting attorney general of the United States just refused to follow this path under similar circumstances. And a preemptive recusal would be a concession of sorts that James’s behavior was inconsistent with the role she has been elected to fulfill.

Perhaps Whitaker’s action gives James some precedential cover. The trouble is that it’s not the sort of cover she might need and want. It’s arguably a bad precedent, after all.

At a minimum, here’s something James could do: stop talking about the investigation. Now. Immediately. Completely.

The choice is hers, but she ought to fully and deeply appreciate that injudicious comments undermine her office and her cases—legally and factually—and will call into question, in the public eye, the credibility of her work.

And the fact that some members of the public might favor charging Trump over constraining Mueller, or might prefer James to Whitaker, is of no moment. That is not the way the American system of justice was designed to work. Picking sides here is dangerous and foolish.

There is at least one high-profile person who has perfectly and precisely threaded this needle: Bob Mueller, who does all his talking in court. Good luck in finding an intemperate Mueller comment from before he became Special Counsel, let alone after. That’s what prosecutorial professionalism looks like.