The U.S. Supreme Court building in Washington. (Jonathan Ernst/Reuters)

The Protect Democracy group, founded by some alumni of the Obama administration with a focus on preventing executive-branch overreach and demanding transparency and accountability, has filed an amicus brief in the U.S. district court in Arizona scheduled to hold a hearing at the beginning of next month to consider vacating former sheriff Joe Arpaio’s conviction after President Trump pardoned him.

The group reasons: “Before it may act based on the Arpaio Pardon, the Court must necessarily determine whether that pardon is valid and binding.” It lays out three arguments for challenging the pardon.

First, Protect Democracy argues:

Due process is violated if the President can eviscerate a court’s ability to ensure compliance with the law by those who wrong the rights of private parties. And as the Supreme Court has explained, “the Due Process Clause was intended to prevent government officials from abusing their power, or employing it as an instrument of oppression.” … When private litigants went to court in this district to protect their constitutional rights against Mr. Arpaio, the court issued orders to provide them relief under the law. When those orders were ignored, the courts entered an escalating series of contempts to enforce compliance with the law and ensure the protection of private parties’ constitutional rights. The Arpaio Pardon violates the Due Process Clause by limiting the protection of private rights, rendering the due process guaranteed by law an empty promise.

Here, Arpaio may argue that the ruling prohibiting the sheriff’s office from abusing the rights of suspected illegal immigrants still stands; Trump pardoned him personally only from punishment for criminal contempt.

That brings us to the second argument, namely that the pardon exceeds Trump’s pardon authority because Article II allows only for  “pardons of offenses ‘against the United States,’ not of contempt orders that arise to enforce the rights of private litigants.”

Third, Protect Democracy argues that “the Arpaio Pardon violates the separation of powers because it unconstitutionally interferes with the inherent powers of the Judicial Branch. The Supreme Court has held that the ability to issue criminal contempt orders is essential to the Article III judicial power and the administration of justice. … The Arpaio Pardon, which would blunt a court’s valid and binding exercise of judicial power to safeguard the rights of private parties, impermissibly transgresses Article III.”

These arguments never have been litigated because no president has extended the presidential pardon power in quite the way Trump did when he made common cause with a state official who refused to abide by the Constitution and by a federal court’s order. It’s the classic case of first impression. We don’t know if the court will even entertain the arguments. Although the odds are long that a district court would seek to undo a presidential pardon, the importance of the arguments should not be ignored for a couple of reasons.

For starters, the arguments outlined in the brief would be entirely proper in an article of impeachment that alleged the president abused his authority by seeking to reward an official who defied a federal court, thereby violating Trump’s oath to faithfully execute his office and enforce the Constitution. As Protect Democracy argues, “The Arpaio Pardon threatens our constitutional system for yet an additional reason: it breaches the President’s oath to protect and defend the Constitution, see Article II, Section 1, Clause 2, and his duty to faithfully execute the laws, see Article II, Section 3. The Arpaio Pardon does not faithfully execute the law; it sends a signal that public officials, so long as they are allies of the President, need not execute the law at all. The President cannot use the pardon power to invite other public officials to violate people’s constitutional rights.” The district court might not prove to be the correct forum for this argument, but it surely is the right argument to build the case as to why Trump should no longer remain president.

Moreover, the backlash in the Arpaio pardon should remind Trump and those witnesses facing a grand jury that his pardon powers are not unlimited. The brief, for example, goes out of its way to remind us that “presidents may only pardon federal offenses, not state offenses.” If Trump’s associates and family members think Trump has an unlimited “get out of jail free” card so they need only protect him to spare themselves, they may want to rethink their assumptions.

Lying to FBI officials, a congressional committee or a grand jury, for example, may be the sorts of offenses that trigger separation of powers concerns. Pardons of this type certainly would intensify impeachment talk. As such, Trump may be more hesitant to wipe the slate clean for former aides by testing the patience of courts, the special prosecutor and/or Congress. In that regard, they should look at the Arpaio case not as a hint of help but as a warning sign that they should not risk their careers and freedoms by being anything less than forthcoming and entirely truthful in their testimony.