Six members of Baltimore's congressional delegation took the unusual step last week of sending Mayor Stephanie Rawlings-Blake and the U.S. Department of Justice a letter expressing concern about the pace of negotiations over a consent decree mandating reforms in the city's Police Department. The mayor wrote back, saying that the process, which began after Freddie Gray's death led to riots, is proceeding apace or faster than similar negotiations in other cities. She acknowledged, however, that it won't be complete before she leaves office, as had originally been hoped.

But that's not the change in administrations the representatives and senators were worried about. Mayor-elect Catherine Pugh is not the problem. Donald Trump is. The candidate who intoned the words “law and order” repeatedly in his acceptance speech at the Republican National Convention last summer has made clear that he favors the kind of aggressive law enforcement tactics the DOJ and Baltimore Police Department are attempting to root out. Mr. Trump said during one of the debates this fall that the failure to employ tactics like stop-and-frisk was “very unfair” to minorities in America's inner cities, but the experience of Baltimore, where similar tactics led to mass arrests on questionable pretexts during the Martin O'Malley era, was precisely the opposite.

If there weren't enough signs already that Mr. Trump's administration wouldn't be as aggressive about using the tools available to the DOJ to enforce reforms in local police departments, his selection of Alabama Sen. Jeff Sessions as his nominee for attorney general should set off a huge alarm.

Senator Sessions said during a Senate committee hearing last year that “the kinds of problems we're seeing and the legal actions that have been taken and the marches in protest about police do have the tendency to cause [police] ... to stay under the shade tree, and not walk the streets.”

Specifically, he has criticized the use of consent decrees to mandate reforms. In the foreword to a 2008 paper on consent decrees by the Alabama Policy Institute, he wrote:

“One of the most dangerous, and rarely discussed, exercises of raw power is the issuance of expansive court decrees. Consent decrees have a profound effect on our legal system as they constitute an end run around the democratic process. Such decrees are particularly offensive when certain governmental agencies secretly delight in being sued because they hope a settlement will be reached resulting in the agency receiving more money than what the legislative branch or other funding source would otherwise have deemed justified. Thus, the taxpayers ultimately fund the settlement enacted through this undemocratic process.

“A consent decree is the equivalent of a legislative enactment created at the hands of the courts, and often less subject to modification. By entering into these decrees, current state executives, such as governors or attorneys general, can bind the hands of future state executives and legislatures. A predecessor's consent decree is difficult to alter or end; in practice, a decree can last for many years — longer than the remedy that was needed.”

We're not sure how much more clearly Mr. Sessions could have expressed his distaste for precisely the kind of settlement Ms. Rawlings-Blake is negotiating and which this city needs if it is to rebuild the trust between the community and the police. Some of the reforms that would be necessary to fully address the problems cited in the DOJ's report on Baltimore's Police Department will be expensive. They will likely involve new recruitment and training practices, better technology, efforts to retain experienced officers and increased oversight. Mayor Rawlings-Blake has already asked the state for assistance in meeting some anticipated costs, and Ms. Pugh and the incoming City Council will be on the hook to figure out how to pay for whatever the governor and legislature don't cover.

That kind of dynamic has caused problems elsewhere. Early this year, the City Council in Ferguson, Mo., balked at the projected costs of the consent decree that city entered into after the riots sparked by the death of Michael Brown, and the DOJ promptly sued. The two parties settled two months later. That wouldn't have happened if Attorney General Loretta Lynch had not been committed to using the power of her agency to force the issue.

It's not necessary for the federal government and the city to come to an agreement before Ms. Rawlings-Blake leaves office. In fact, it might be preferable for Ms. Pugh to have her fingerprints on the deal — she will be the one who will have to see it through, and she should have some ownership of it. But it is absolutely imperative for it to be finalized before Jan. 20, the day Mr. Trump is to be inaugurated. Once a deal is accepted by the courts, a federal judge will have the power to see that it is enforced, no matter who is attorney general. But if that doesn't happen before Mr. Trump arrives, Baltimore's police reform effort will be at risk.