Judges have traditionally enjoyed such leeway in meting out jail terms that one prisoner could serve many times as long as another for a similar crime. Concerned about unfair -- and often overly lenient -- sentences, Congress in 1984 created the U.S. Sentencing Commission, which issued a manual that greatly restricts judges' discretion in sentencing 40,000 federal defendants a year. The new system, for crimes committed since Nov. 1, 1987, also abolished parole and sharply limited probation and time off for good behavior.
Defense lawyers quickly launched a legal assault against the new system. The result was chaos, with 158 federal...