Democrats on the House Judiciary Committee won’t let President Donald Trump’s pardon of Joe Arpaio go without a fight.

The committee members, led by John Conyers Jr. of Michigan and Zoe Lofgren of California, wrote to committee chairman Bob Goodlatte (R-VA) asking him to investigate the pardon of the controversial former sheriff.

“The pardon not only disregards the rule of law, it directly flouts the courts themselves by signaling that it is acceptable for parties to ignore court orders,” the committee wrote.

Two of the primary complaints against Trump include that he did not follow Justice Department policy, which calls for waiting five years or more before considering the pardon and waiting for an expression of remorse from Arpaio, and that before pardoning Arpaio he asked Attorney General Jeff Sessions to drop the criminal case.

The letter called the pardon a “gross injustice” and went on to detail the offenses Arpaio was convicted of. Although the members acknowledged the broad pardoning power of the president, they stated that the power can still be abused and Arpaio was “not worthy of reprieve.”

Arpaio was convicted for intentionally disobeying a judge’s order in an immigration case, specifically the order to stop targeting immigrants with traffic patrols.

For reference, here is what the constitution says about presidential pardons:

Article II, Section 2, Clause 1 of the Constitution says: “The President … shall have Power to grant Reprieves and Pardons for Offences against the United States, except in Cases of Impeachment.” The president’s power can only be used to pardon someone for a federal crime, not a state one.

Read the full text of the letter here.