President Trump is reportedly looking into using his pardon power in response to an expanding special counsel investigation of Russian influence in the 2016 election. If he really did pardon his aides, his family or himself to head off Robert Mueller’s inquiry, the move probably would be constitutional but ultimately self-defeating for the president.

In using his power to pardon potential witnesses against him, Trump probably would convert a weak criminal investigation into a full-fledged impeachment effort. In 1833, Chief Justice John Marshall upheld a presidential pardon by Andrew Jackson by saying that a pardon is “an act of grace” by a president. A pardon in these circumstances would not be viewed as an act of grace, but a gratuity from an isolated president.

Trump clearly possesses the authority to pardon associates and family members under Article II, Section 2 of the U.S. Constitution, which states that the president “shall have power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.” Although presidents have tended to wait for convictions before issuing pardons, Trump can do so in anticipation of federal charges. In Ex parte Garland in 1866, the Supreme Court ruled that the pardon power “may be exercised at any time after its commission, either before legal proceedings are taken, or during their pendency, or after conviction and judgment.” That is precisely what Gerald Ford did when he pardoned Richard Nixon before any charges were brought against him.