The Supreme Court seemed reluctant Tuesday to grant the Securities and Exchange Commission greater leeway in seeking penalties against companies that commit fraud.

Justices across the ideological spectrum suggested that the government was asking for too much in its reading of a statute that sets time limits on when regulatory agencies can file civil complaints.

The law says the actions must be filed within five years of the violation, but the government contends that in fraud cases, that means five years from the time an agency discovered, or should have discovered, a violation.

Justice Antonin Scalia said that was a “brand new” government claim that has no grounding in the court’s precedents. “What’s extraordinary is that the government has never asserted this, except in the 19th century, when it was rebuffed and repudiated its position,” he said.

Justice Stephen G. Breyer said he worried that the statute applies not just to SEC actions but “all government actions, which is a huge category across the board.”

He added: “The reason I brought up Social Security, Veterans Affairs, Medicare is it seems to me to have enormous consequences for the government suddenly to try to assert a quasi-criminal penalty and abolish the statute of limitations, I mean, in a vast set of cases.”

Assistant Solicitor General Jeffrey B. Wall warned the justices against “feverish hypotheticals” and said the government simply needs a bit more time in some complex cases in which fraud makes it difficult to ascertain when violations began.

The SEC has pursued 25 cases involving the kinds of violations at issue, Wall said, and 19 were brought within the five-year limit. The longest one dated back 61 / 2 years, he said.

The case before the court is Gabelli v. SEC and involves Marc Gabelli, a portfolio manager, and Bruce Alpert, chief operating officer at Gabelli Funds. The SEC accuses them of authorizing an investor in one of their firm’s mutual funds to engage in an improper trading technique known as “market timing.”

The alleged activity took place between 1999 and 2002. The SEC’s investigation began in fall 2003, and the agency filed its civil complaint in April 2008.

New York lawyer Lewis Liman, representing Gabelli and Alpert, said the government was trying to get around the clear wording of the law.

“This case concerns the statute dealing exclusively with penalty claims brought by government agencies to punish conduct made unlawful by statute,” Liman said. “Congress provided a clear and easily administered statutory time limitation on the government’s power to punish: five years.”

In other action Tuesday, the court decided unanimously that state prisoners are not entitled to delays in the federal appeals of their convictions even if they are mentally incompetent to help their attorneys.

The decision overturned appeals-court rulings that had granted two men on death row indefinite stays in federal court until their mental conditions improved.

The decision affects convicts who are challenging those actions in federal court. Inquiries into whether the defendant received a fair trail depend upon what happened in the lower courts, Justice Clarence Thomas wrote, not new information from the client.

“Given the backward-looking, record-based nature of most federal habeas proceedings, counsel can generally provide effective representation to a habeas petitioner regardless of the petitioner’s competence,” Thomas wrote for the court.

There may be limited cases in which a district judge decides that a defendant must be able to aid the attorney representing him, Thomas said.

But he said in those limited cases, district judges should take into account “the likelihood that the petitioner will regain competence in the foreseeable future.”

“Where there is no reasonable hope of competence, a stay is inappropriate and merely frustrates the state’s attempts to defend its presumptively valid judgment,” he said.

The ruling does not touch on the court’s decisions that require competence before a defendant can be tried or its prohibition on executing the insane.

The decision overturned rulings by the U.S. Courts of Appeals for the 9th and 6th circuits. One involved Ernest Valencia Gonzales, sentenced to death for stabbing a man and his wife in front of their child during a burglary, and Sean Carter, convicted by an Ohio jury of murdering and raping his adoptive grandmother.

The cases are Ryan v. Gonzales and Tibbals v. Carter.