Democratic presidential nominee Hillary Clinton, right, listens to Republican presidential nominee Donald Trump, left, during the second presidential debate at Washington University in St. Louis, Sunday, Oct. 9, 2016. Democratic presidential nominee Hillary Clinton, right, listens to Republican presidential nominee Donald Trump, left, during the second presidential debate at Washington University in St. Louis, Sunday, Oct. 9, 2016.

Republican presidential nominee Donald Trump’s model for U.S. Supreme Court nominees—the late Justice Antonin Scalia—was no fan of a long-expired independent counsel process that, he said, eroded executive power.

But even Scalia might find some problems with Trump’s promise, if elected, to have a special prosecutor investigate Hillary Clinton, the Democratic presidential nominee.

The justice might not have not found constitutional fault with the current process for appointing special prosecutors. But Trump’s threat of an investigation of and jail for Clinton could have given Scalia pause about fairness.

“The use of the special prosecutor has ordinarily been to reassure the public of no political agenda or conflicts,” said Katy Harriger of Wake Forest University, who wrote The Special Prosecutor in American Politics. “You could certainly say announcing during the presidential debate that you’re going to have one to investigate your opponent goes against the spirit of why we had them in the past.”

Here’s what Trump said Sunday night at the debate in St. Louis: “I didn’t think I’d say this, but I’m going to say it, and I hate to say it. But if I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation, because there has never been so many lies, so much deception. There has never been anything like it, and we’re going to have a special prosecutor.”

Clinton responded: “It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country.” To which Trump rebounded: “Because you’d be in jail.”

Trump’s remarks, rooted in the email scandal that has haunted Clinton, swiftly drew criticism from liberals and conservatives. Former U.S. Attorney General Eric Holder Jr. said on Twitter: “Be afraid of any candidate who says he will order DOJ/FBI to act on his command.” Ari Fleischer, a former George W. Bush spokesman, posted this on Twitter: “Presidents don’t threaten prosecution of individuals. Trump is wrong on this.”

One of Scalia’s most heralded dissents came in 1988′s Morrison v. Olson. In that case, the high court, ruling 7-1, upheld the constitutionality of the independent counsel provisions of the Ethics in Government Act of 1978. A lower federal appellate court had struck down the provisions as violating the separation of powers and the appointments clause of the Constitution.

For Scalia, the Constitution’s vesting of executive power in the president meant all executive power. The independent counsel provisions, he wrote, reduced the amount of control that the attorney general, and through him, the president exercised over the investigation and prosecution of a class of criminal activity. Particularly problematic was the appointment of the counsel by a special three-judge court after referral by the attorney general.

Scalia was keenly aware of the “vast power and immense discretion” of prosecutors generally.

In his dissent, he quoted from a speech by Justice Robert Jackson, a former U.S. attorney general, in which he said: “If the prosecutor is obliged to choose his case, it follows that he can choose his defendants. Therein is the most dangerous power of the prosecutor: that he will pick people that he thinks he should get, rather than cases that need to be prosecuted.”

Jackson continued: “It is in this realm—in which the prosecutor picks some person whom he dislikes or desires to embarrass, or selects some group of unpopular persons and then looks for an offense, that the greatest danger of abuse of prosecuting power lies. It is here that law enforcement becomes personal, and the real crime becomes that of being unpopular with the predominant or governing group, being attached to the wrong political views, or being personally obnoxious to or in the way of the prosecutor himself.”

Scalia ultimately had faith in the “primary check” against prosecutorial abuse: political fallout.

“If federal prosecutors ‘pick people that [they] thin[k] [they] should get, rather than cases that need to be prosecuted,’ if they amass many more resources against a particular prominent individual, or against a particular class of political protesters, or against members of a particular political party, than the gravity of the alleged offenses or the record of successful prosecutions seems to warrant, the unfairness will come home to roost in the Oval Office,” he wrote.

Harriger called it a “pipe dream” to believe politics can be removed from the investigation and prosecution of high-level officials. Trump’s Sunday statement “flies in the face” of how special prosecutors are normally used, she said.

The 1978 statute was allowed to expire in 1999 after some very controversial, expensive and long independent counsel investigations.

“My conclusion after spending a good decade of my life on it was it has some symbolic value in part to try to diffuse the political context but the process itself had become so politicized it was hard for independent counsels to be perceived as independent,” Harriger said. “They were damned if they did prosecute and damned if they didn’t when they made decisions not to prosecute. Look at what [FBI Director James] Comey is going through with the Clinton emails.”

The 1978 statute was enacted in reaction to Watergate. After the law expired, the attorney general in 1999 issued regulations for the appointment of outside, temporary counsels in certain circumstances.

These “special counsels” are appointed by and answerable to the attorney general. They have less independence than independent counsels under the 1978 law and less than the “special prosecutors” appointed in the Watergate matter.

Trump may “direct” his attorney general to appoint a special counsel but the regulations give that attorney general total discretion.

That unfettered discretion has drawn its own criticism.

Former independent counsel Carol Elder Bruce of K&L Gates has testified before Congress and written in a New York Times article that the special counsel regulations in place now “do not have the force of law and fall short of the post-Watergate promise of independence by, for example, requiring that the special prosecutor consult with the attorney general before taking certain actions.”

The public, according to Bruce’s New York Times piece, “should not have to rely entirely on the unilateral judgment of an attorney general as to when and whom to appoint and what authority to delegate when it comes to conflict-of-interest referrals.”

There’s no double jeopardy issue in play because Clinton wasn’t charged with a crime as a result of the FBI investigation, some experts said. Indeed, the FBI investigation found no reason to prosecute her.

Even if a President Trump were to get a special prosecutor, there could be difficulties going after Clinton over her deletion of thousands of emails: It might be hard to find anything new considering the depth of the FBI’s investigation.

“The evidence has been stepped on, and people have already been interviewed over and over again,” Harriger said. “They know what will be asked.”

Contact Marcia Coyle at [email protected]. On Twitter: @MarciaCoyle.