In Mr. Angelos's case, the drug offenses and related money-laundering convictions, for using drug money to buy a car and pay his rent, could subject him to eight years in prison. The mandatory minimums are for the additional offense of carrying a gun while selling drugs. Mr. Angelos carried a Glock pistol in an ankle holster when he sold marijuana on two occasions, though he did not brandish or use it. More guns were found in a briefcase and a safe at his home.

According to the indictment, some of the guns were stolen, though Mr. Angelos was not accused of being the thief. Judge Cassell is required to add five years for the gun in the first deal and 25 years each for the second deal and the guns found at his home.

The Supreme Court will decide whether to strike down the sentencing guidelines after it hears arguments in October, and some legislators are already signaling their preference for more mandatory minimums if the guidelines are deemed unconstitutional.

At a hearing in July on legislation that would increase drug sentences, Representative Howard Coble, Republican of North Carolina, said, "It seems clear that mandatory minimums may well take on added importance in assuring appropriate sentences for serious federal crimes as a result of the Supreme Court's actions."

Ronald H. Weich, a former counsel to the Senate Judiciary Committee who opposes mandatory minimums, said they had a political constituency. "There is a real danger," Mr. Weich said, "that we're heading back to mandatory minimums if guidelines are unconstitutional."

The Justice Department supports mandatory minimums, said Monica Goodling, a spokeswoman.

"Tough but fair mandatory minimum sentences take habitual lawbreakers off the streets, lock up the most dangerous criminals and help ensure the safety of law-abiding Americans," Ms. Goodling said. "Since these common-sense policies were created, we've seen crime plummet to a 30-year low. The public, the Congress and presidents of both parties have supported mandatory minimums for a simple reason -- they work."

In June, just days after the Supreme Court's decision in Blakely v. Washington, which struck down the sentencing system of Washington State, Judge Cassell was the first judge to say the logic of the decision required the voiding of the federal sentencing guidelines as well. In the Angelos case, he wrote that he took "no joy" in the "potentially cataclysmic implications" of that reasoning.