LAST WEEK, President Bush continued his unusually churlish approach to mercy, granting six pardons to people who had long ago served their sentences and rejoined society. Mr. Bush, in most areas aggressive in his exercise of presidential powers, has been timid when it comes to clemency. In his first term, he has issued a scant 25 pardons and two commutations of sentences; this is dramatically fewer than any other recent president and less than 5 percent of the number of clemency actions by President Jimmy Carter alone. What's more, all of Mr. Bush's pardons, like the current round, have been intended to court no controversy. His only public displays of the presidential power to forgive, a power that the founders specifically placed in the Constitution and wrote about with great reverence, are reserved for Thanksgiving turkeys.

Mr. Bush's caution is understandable. Both his father and President Bill Clinton left office in controversy over last-minute pardons. But the proper response to the disrepute that Mr. Clinton brought to the pardon power by giving grace to fugitive financier Marc Rich and others unworthy of it is not to let the power lapse into disuse. The founders understood, as Alexander Hamilton wrote, that without a presidential check on the court system, "justice would wear a countenance too sanguinary and cruel." That is even truer today. The enormous growth in federal law enforcement, coupled with inflexible and sometimes grotesque sentencing rules, makes pardons a critical palliative on the criminal justice system -- that is, if a president is courageous enough to use them.

One of Mr. Bush's judicial nominees, Utah federal judge Paul G. Cassell, recently imposed a mandatory sentence of 55 years on Weldon H. Angelos, a first-time offender convicted of drug and firearms charges. In handing down the sentence, Judge Cassell, a noted conservative and former law professor, described it as "unjust, cruel and irrational" and called on Mr. Bush to commute it. In an age of mandatory minimum drug sentencing, can Mr. Bush identify no federal inmates whose sentences he considers excessive?