The annual convention last weekend in Washington of the conservative Federalist Society — a.k.a. President Trump's sole-source supplier of judges — included something of a surprise.

It was the eyebrow-raising emergence of a group of conservative and libertarian lawyers, mostly society members, concerned about Trump's bull-in-the-china-shop regard for basic rules of law.

Think, for example, of Trump's proposed executive order to nullify the 14th Amendment guarantee of birthright citizenship.

The new group, Checks and Balances, avows it is "standing up for the principles of constitutional governance."

And this is from Trump's side of the aisle. And his own isle of judicial nominees.

It started with 14 signers, including former White House and Justice Department officials in past GOP administrations, litigators, law professors, and former Homeland Security Secretary and Pennsylvania Gov. Tom Ridge.

It held a luncheon for Federalist Society convention attendees, quickly assembled a mailing list of hundreds, and started a website and a Twitter account (@chkbal) that as of Tuesday afternoon had more than 17,000 followers.

The group was organized by conservative lawyer and Trump critic George Conway, a society member and husband of Trump adviser Kellyanne Conway.

But he and others note that the group's efforts aren't aimed at the Federalist Society (whose mission statement is similar to Checks and Balances'), and emerge despite satisfaction with Trump's judicial picks, especially for the Supreme Court.

So, not about politics. Not about Trump. Except that it's clearly about Trump.

One of the group's principals is Philadelphia native Jonathan Adler, director of Case Western Law School's Center for Business Law and Regulation.

"The goal is to make sure there's a right-of-center voice for rule-of-law values," he says, "To make sure such values and the power of truth are preserved at a time in which partisanship and tribal loyalty risk undermining them."

Impetus for the group grew out of concern that following this year's midterm elections, the White House would seek greater control over the Justice Department and special counsel Robert Mueller's investigation into any Russian involvement in the 2016 presidential election.

The immediate post-midterms firing of Attorney General Jeff Sessions and the appointment of his chief of staff, Matt Whitaker, as acting attorney general did not ease those concerns.

Whitaker's upgrade brought bipartisan criticism and litigation — a constitutional challenge from Democratic senators arguing that his position requires Senate confirmation.

Adler says Checks & Balances immediately drew fire from right-wing groups such as American Greatness and on social media, including charges of "giving comfort to the enemy" and being financed by wealthy liberals.

But, he says, "none of us are getting paid to do this…[and] to believe in the values of law and believe they are under siege does not put you on any one part of the political spectrum."

Wider areas of concern to Checks and Balances include preserving the separation of powers, and the independence of the criminal justice system and the judiciary — all of which should come before politics.

Ridge could not be reached for comment, but told the New York Times he's concerned about the independent judiciary. "Regardless of whether you're a Republican or Democrat, liberal or conservative," he told the newspaper, "you embrace the rule of law."

The question: Can upstart movements such as this be sustained and make a difference and, more immediately, have any impact on the actions of the president?

Adler says he hopes the group expands, holds events to highlight its concerns, and conducts forums for debate as constitutional issues arise.

Constitutional law professor Bruce Ledewitz of Duquesne University Law School calls the movement "very encouraging," but hopes it extends beyond tracking Trump to broader issues related to fighting partisanship in the legal process.

He also says, "I would love to see a similar movement from lawyers on the left."

Still, Checks and Balances seems like a well-intentioned, right-minded idea, in the category of: What could it hurt?

And, as Penn Law constitutional expert Seth Kreimer put it, "Any voices supporting the rule of law are welcome in these times."