Joe Arpaio, the former sheriff from Arizona, is expected to go before a judge once again today, this time to argue that his guilty verdict should be expunged from his record after President Trump pardoned him in August. The federal judge in his case, Susan Bolton, scheduled oral arguments to determine whether she should void Arpaio’s conviction for criminal contempt. However it shakes out, one thing is clear: The use of pardons (and sentence commutations) has changed over the past few decades — and controversial cases like Arpaio’s could make it harder to go back.

Today’s system is very different from the executive’s use of clemency power as envisioned by the framers of the Constitution. It was originally intended to be deployed as a corrective mechanism against abuses in the justice system or as a bargaining chip against rebellions to keep the peace, according to students of historical pardons. Now pardons and commutations are used much less frequently — Arpaio’s pardon is Trump’s only act of clemency so far — and as a result, some legal experts say that an important check on the justice system has fallen into disuse.

“The founders expected the pardon power to be used somewhat routinely because they acknowledged that the justice system isn’t always fair, and that government forgiveness can serve an important political purpose,” said Daniel Kobil, a professor of law at Capital University Law School. “But recent presidents have basically allowed this power to atrophy, to the detriment of many people who might benefit from it.”

The uses of clemency that get headlines these days — such as that of Arpaio, whom Trump pardoned after Bolton ruled that he had breached another judge’s order to stop racially profiling Latinos but before he had been sentenced — are typically for high-profile figures rather than ordinary people.

Historically, recipients of pardons have been anonymous offenders who have served their time and aren’t contesting their guilt; indeed, to receive a pardon, it’s helpful for petitioners to express contrition and take responsibility for their crime, according to the office of the pardon attorney in the Department of Justice, which evaluates petitions for clemency and recommends candidates to the president. (Although pardons do remove punishment and reinstate civil rights revoked by federal convictions, they don’t imply innocence or wipe an offender’s slate clean.) Instead of seeking a clean record, petitioners may want to regain one of the privileges of citizenship denied to felons, like gun ownership or a medical license.

Scholars worry that the more the pardon becomes associated with contentious cases like Arpaio, the more difficult it will be for future presidents to justify pardons for ordinary citizens caught on the wrong side of the justice system. The attention that cases such as Arpaio’s receive may have helped create the impression among members of the public that pardons are a coveted “get out of jail free card” conferred by the president with very little vetting. Indeed, Arpaio didn’t even ask for a pardon. And these high-profile pardons tend to be very unpopular — Gerald Ford’s famous pardon of Richard Nixon may have cost him re-election. Ironically, though, the government has made the standards for non-celebrity cases — the pardons that are closest to the original conception of the clemency power — increasingly high. This is one reason for the decrease in the number of pardons and commutations issued in recent decades. Barack Obama, who granted more than 1,000 commutations toward the end of his presidency, was a notable exception to this decline, although like previous presidents, he granted relatively few pardons. The other major factor, pardon experts say, was politicians’ increased wariness about appearing soft on crime, starting during the presidency of Ronald Reagan.

The pardon was a common feature of English law, on which much of the U.S. legal system is based, said Rachel Barkow, a professor at the New York University School of Law. In England, the pardon was frequently deployed to counterbalance laws for which the monarch believed the punishment outweighed the crime. For the founders of the United States, “the pardon was a way for the president to control federal prosecutions that go too far and legislators who pass laws that are too severe,” Barkow said.

The pardon was also a handy tool for presidents trying to restore peace after insurrections. George Washington put it to work to forgive people who had been charged with treason for their participation in the Whiskey Rebellion by giving them clemency after they ended the rebellion.

Until the late 19th century, pardons were largely granted ad hoc. Sometimes judges and prosecutors brought to the president cases in which they felt the law was too inflexible or the wrong outcome had been reached, said Margaret Love, who served as the pardon attorney between 1990 and 1997. Love has studied early pardons and found records of Thomas Jefferson receiving not one but two petitions from judges on behalf of convicted goose thieves in a single two-week period. (Jefferson, confused, wrote in the margin of the second petition, “Is not this the same which was directed last week?”)

But many of those seeking relief appealed to the president directly. Abraham Lincoln famously received pardon applicants at the White House, to the irritation of his staff, who felt that the president was too easily moved by petitioners’ stories. Lincoln pardoned Union deserters during the Civil War, and he and his successor, Andrew Johnson, both pardoned Confederate soldiers during and after the war ended. Although Johnson’s decision to pardon the Confederates helped motivate his impeachment, both presidents justified the pardons by arguing that they helped restore the health and unity of the nation.

After its establishment in 1870, the Department of Justice assumed responsibility for the pardoning process. And the first big shift in the way pardons were handed down came in 1910, with the establishment of the federal parole system. It offered another route for the reduction of harsh sentences, so presidents no longer had to rely as heavily on clemency.

Presidential clemency continued to be used as a means of restoring rights after an individual had served his or her sentence, however, and, like the use of the pardon to end rebellions, as a strategy for pursuing policy goals. Woodrow Wilson, irritated with Congress for refusing to repeal Prohibition, granted clemency to large numbers of violators. Other presidents used large-scale pardons to acknowledge policy mistakes or a shift in social norms. Both Ford and Jimmy Carter offered clemency to Vietnam-era draft dodgers after the war was over, and Obama commuted the sentences of hundreds of nonviolent drug offenders sentenced under laws that overwhelmingly affected black men.

The advent of Reagan’s war on drugs and the tough-on-crime politics of the 1980s and early 1990s, however, resulted both in a larger population of people who might request clemency and presidents who seemed increasingly wary of handing them out. The call for “truth in sentencing” policies resulted in the abolishment of federal parole in the late 1980s, which exacerbated the situation. Reagan issued fewer pardons and commutations than his predecessor, Carter, despite serving twice as long.

“There was a perfect storm in the ’80s when more and more people were in prison but there was no relief except for this creaky mechanism, the pardon,” Love said. “And the president didn’t want to use it. The party line was, ‘Just say no.’”

The political liability associated with pardoning an offender who might go on to commit a shocking crime was cast into sharp relief during the 1988 presidential campaign. Vice President George H.W. Bush lambasted his Democratic opponent, Massachusetts Gov. Michael Dukakis, for a weekend furlough program established by the state government that resulted in an inmate, William Horton, committing several violent crimes while out of prison.

“I think it’s not a coincidence that Bush was very stingy in the use of his clemency power,” Kobil said. Subsequent presidents have also issued relatively few pardons and commutations and began to wait until the end of their term to grant clemency in any significant numbers.

In addition to the general decline in the overall number of pardons and commutations, the share of pardons and commutations granted has also dropped in the past few decades. That’s largely because of the increased number of people eligible for clemency and presidents’ unwillingness to issue pardons or commutations.

But there’s also a more mundane reason why so few petitions for clemency are successful: The bureaucratic process for evaluating them has grown increasingly byzantine and possibly even hostile to the notion of pardoning. Petitioners must now submit their request to the office of the pardon attorney and the application makes its way through half a dozen layers of government bureaucracy before arriving on the president’s desk.

“At any point, if someone thinks this isn’t a good case, it dies there,” Barkow said. “Many of the people looking at the petitions are also prosecutors. You can imagine why so few make it through.”

The handful of pardons that do make headlines, including Arpaio’s, are generally not vetted in this manner — in fact, many people may be unaware that it’s unusual for a pardon not to receive extensive vetting. This creates a perception, according to Love, that the pardon is a privilege, not an obligation, of the presidency. And as the pardon becomes associated with unpopular, high-profile cases, it becomes more difficult for presidents to justify granting clemency to large numbers of ordinary citizens, as they did in the past. “Pardons are seen as favors granted at the last minute, kind of like running off with the White House china,” she said. “It’s no longer perceived as something the president should routinely do as a check on the justice system.”