President Trump, with Vice President Pence, at the White House on Thursday. (Jabin Botsford/The Washington Post)

This week, President Trump reportedly told aides that he wants to expedite construction of his border wall and that if they have to break any laws to get it done, not to worry: He will pardon them. Democratic members of Congress vowed to investigate this alleged abuse of power. The White House quickly responded that Trump was just joking, the apparent go-to defense whenever the president is caught saying something outrageous or potentially criminal. But, if serious, Trump’s offer would be more than a flagrant abuse of the pardon power — it could also violate federal bribery law. That has implications not only for impeachment inquiries, but also for potential future criminal proceedings.

Trump’s exercise of the pardon power has been unconventional, to say the least. He has largely disregarded the established processes for reviewing pardon requests through the Department of Justice’s Office of the Pardon Attorney, seemingly preferring to act on personal whim or political sympathies. And he has granted pardons to some controversial figures, including former Arizona sheriff Joe Arpaio and conservative commentator Dinesh D’Souza.

But it’s one thing to flout normal procedures for granting pardons to those already convicted of past crimes unrelated to the president. It’s quite another for a president to use the promise of future pardons to encourage unlawful behavior by members of his own administration. The latter is truly corrupt: signaling to aides that they may freely disregard the nation’s laws because the rules don’t apply to those who do the president’s bidding.

This isn’t the first time Trump has been accused of unlawfully wielding the pardon power. Then-special counsel Robert S. Mueller III investigated allegations that the president may have obstructed justice by dangling pardons in front of potential witnesses against him, including former campaign chairman Paul Manafort. Although Mueller declined to reach a conclusion on obstruction, he found that “the President intended to encourage Manafort to not cooperate with the government” by repeatedly praising Manafort and holding out the possibility of a pardon.

This more recent offer of pardons for breaking the law to build the wall probably would not constitute obstruction of justice, because it is not connected to any official proceeding. But offering a pardon for such illegal acts could easily violate the federal bribery statute, 18 U.S.C. 201. That law makes it a crime to give, offer, or promise “anything of value” to a federal public official to influence the official in the performance of an official act or induce the official to violate his or her lawful duty.

Those who work in the Trump administration are public officials under this statute. “Anything of value” is construed very broadly and goes far beyond briefcases full of cash. It includes intangibles with subjective value to the official that could influence the official’s behavior — a “get out of jail free” card in the form of a guaranteed pardon, for example. The charge would be that Trump offered a pardon to public officials to influence the performance of official acts connected to building the wall or to induce the officials to violate their duties by breaking the law.

If there were evidence Trump made such a proposal, legally it wouldn’t matter whether the official actually ended up breaking the law or receiving a pardon. It wouldn’t even matter whether the official agreed to the proposal. The crime of bribery may be established simply upon proof of a corrupt offer.

Whether bribery could actually be proved would depend on the evidence of the president’s intent. If Trump truly was not serious, he would lack the corrupt intent to influence that is necessary to prove a quid pro quo and establish bribery. Such a joke might be foolish or reckless, but not criminal. As in most such cases, the line between innocent behavior and criminality comes down to proof of state of mind, which could include probing whether an alleged “joke” was really a directive via a nod and a wink.

Allegations of bribery may provide additional fodder for impeachment proceedings. The Constitution says that impeachment is justified for “treason, bribery, or other high crimes and misdemeanors.” And even if a sitting president cannot be criminally prosecuted under current Justice Department policy, the Constitution also recognizes that the president is subject to prosecution once he is no longer in office.

If there were compelling evidence that Trump did encourage aides to break the law and promised to pardon them, that sounds like bribery. That’s on top of other legal theories that also could implicate the president, including conspiracy or aiding and abetting any resulting crime. If the allegations turn out to be true, then before leaving office Trump may have yet another reason to confront an unresolved question concerning his pardon power: whether he can pardon himself.

Read more:

Dana Milbank: Why can’t we use nuclear weapons against bedbugs?

Greg Sargent: Behind Trump’s craziness, there’s always corruption. Here’s the latest.

The Post’s View: Trump has no trouble gutting the law to build his wall

Jennifer Rubin: Trump deserves impeachment quite apart from the Mueller report

Michael W. McConnell: Trump’s not wrong about pardoning himself