In two decisions — one a 5-4 split, the other unanimous — the justices found that money laundering charges apply only to profits of an illegal gambling ring and cannot be used when the only evidence of a possible crime is when someone hides large amounts of cash in his car when heading for the border.

The government brings money laundering cases against more than 1,300 people annually and the justices appeared to agree with defense lawyers who said government prosecutors have been stretching the bounds of the law. The Justice Department drew little sympathy from Justice Antonin Scalia.

"The government exaggerates the difficulties" of enforcing a narrowed interpretation of money laundering, Scalia wrote in the gambling case involving an illegal lottery. Scalia drew the support of three other justices. The deciding fifth vote came in a separate opinion from a member of the liberal wing of the court, Justice John Paul Stevens. Stevens declined to go as far as Scalia did in rejecting the government's position.

Weiss pleaded guilty to a racketeering conspiracy charge in April as part of an agreement with prosecutors.

Prosecutors had asked for a 33-month sentence. Weiss and his attorneys had sought a reduced sentence, citing his age and contributions inside and outside courtrooms.

Authorities said the law firm made about $250 million over two decades by filing legal actions on behalf of professional plaintiffs who received $11.3 million in kickbacks.

The firm dominated the industry in securities class-action lawsuits, which involve shareholders who claim they suffered losses because executives misled them about a company's financial condition.

The kickback scheme allowed attorneys at the firm then known as Milberg Weiss to be among the first to file litigation and secure the lucrative position as lead plaintiffs' counsel, according to court documents.

The lawsuits targeted companies such as AT&T Inc., Lucent, WorldCom, Microsoft Corp. and Prudential Insurance.

A seven-year investigation has resulted in guilty pleas by three of Weiss' former partners.

Two defendants remain in the case -- the firm itself, now known as Milberg LLP, and attorney Paul T. Selzer. Trials for those defendants are scheduled in August.

Judge Walter called the kickback scheme "extremely serious" because attorneys such as Weiss had not disclosed to judges handling class-action cases that the lead plaintiffs were paid for their involvement.

In a unanimous decision, Justice Clarence Thomas said that a money laundering case cannot be proven merely by showing that funds were concealed while being transported.

In a 5-4 ruling, Justice Antonin Scalia said that money laundering refers to profits of an illegal operation, not gross receipts. The court's interpretation is a narrow one opposed by law enforcement agencies.

Scalia said the narrow definition will not unduly burden authorities, who must show only that a single instance of unlawful activity was profitable.

In the cases of Efrain Santos and Benedicto Diaz, a federal judge and the 7th U.S. Circuit Court of Appeals in Chicago said that paying off gambling winners and compensating employees who collect the bets don't qualify as money laundering. Those are expenses, and prosecutors must show that profits were used to promote the illegal activity, the appeals court ruled in a decision affirmed by the Supreme Court.

In dissent, Justice Samuel Alito said that the court's ruling would frustrate congressional intent and "maim" a law that was enacted as an important defense against organized criminal enterprises.

In a unanimous decision, Justice Clarence Thomas said that a money laundering case cannot be proven merely by showing that funds were concealed while being transported.

In a separate 5-4 decision, the court said that money laundering refers to profits of an illegal operation, not gross receipts. The court's interpretation is a narrow one opposed by law enforcement agencies.

Justice Antonin Scalia said the narrow definition will not unduly burden authorities, who must show only that a single instance of unlawful activity was profitable.

Providing the crucial tie-breaking vote, Justice John Paul Stevens refused to go as far as Scalia, saying Congress favored a broader interpretation of the law in cases involving the operation of organized crime syndicates.

Without comment, the justices declined to hear the case involving a segment of the $1.5 billion fantasy sports industry in the United States, in which participants manage imaginary teams based on the real-life performances of professional players.

The lawsuit involves C.B.C. Distribution and Marketing Inc., a Missouri company unable to obtain a license from a subsidiary of Major League Baseball to use players' names in C.B.C.'s fantasy baseball games.

The Missouri company sued, saying it did not need a license to continue to sell its fantasy baseball games on its Web site.

The baseball players' union jumped into the case on the league's side, alleging a state law violation of the players' publicity rights — the ability to profit from the commercial use of a person's name.

A federal court and the 8th U.S. Circuit Court of Appeals in St. Louis ruled in favor of the fantasy baseball business, saying that enforcing state law rights would violate C.B.C.'s right of free speech protected by the First Amendment.

The National Football League Players Association supported professional baseball's request that the Supreme Court hear the case.

Class-action law firm Milberg LLP is close to a settlement that could end a federal prosecution of the firm for alleged kickbacks, according to two people familiar with the discussions. The deal would mark the climax of a case that has roiled the American plaintiff's bar.

While a deal could still fall apart, the sides have made progress after weeks of talks that have centered on the payment Milberg will have to make as part of a settlement. Last summer, prosecutors had sought about $50 million in fines and penalties, but the demand mushroomed this year to about $100 million, say people familiar with the negotiations. Recently, Milberg and prosecutors have zeroed in on a payout in the neighborhood of $75 million, these people say.

The government alleged that the firm paid more than $11 million in kickbacks to clients in exchange for their serving as lead plaintiffs in securities class actions. These payouts allowed the firm to quickly file suits and become lead counsel, prosecutors allege, entitling Milberg to a large share of the fees: some $250 million over more than two decades. The firm, which is scheduled to stand trial in August, has denied wrongdoing.