WASHINGTON Vice President Dick Cheney and Halliburton Corp. have asked a federal judge in Dallas to dismiss allegations that they defrauded investors through an accounting tactic that was begun when Cheney was chief executive of the oil services and construction company.

In asking for the dismissal, Cheney and Halliburton are primarily relying on changes in federal law in the 1990s that require shareholders to specify in their initial lawsuit filing exactly how the fraud occurred.

"The complaint is exactly the type of nebulous pleading that the law was intended to prevent: a naked allegation that Halliburton's revenue figures were wrong, coupled with an unsupported assertion that the company's disclosures of accounting principles, although made, simply did not go far enough," according to the motion that was filed Thursday. The company announced the move Friday.

Halliburton is being sued by a dozen shareholders and Judicial Watch, which also named Cheney as a defendant. The suits allege that Halliburton and Cheney in 1998 began counting uncollected debts from construction cost overruns as revenue to raise a sagging bottom line.

The suits allege that the method improperly increased revenue by more than $500 million over the past four years and that Halliburton delayed for a year disclosing the accounting change to shareholders.

"We have the facts, and many of the key facts were in Halliburton's own filings," said Judicial Watch's president, Tom Fitton.

"In a case like this, the numbers speak for themselves. We look forward to the vice president's sworn testimony on the matter."

Attorneys for Cheney and Halliburton further asked for the dismissal of the lawsuits because they "fail to plead with particularity any factual basis for alleging that Halliburton's revenue numbers were wrong, choosing instead to state breezily that revenues from construction claims and change orders were not probable and could not be reliably estimated.'"

Bill Federman, one of the attorneys suing Halliburton, called much of the language in the reply brief "boilerplate." Federman said it was ironic that the motion to dismiss relied on changes in federal law made in the past decade.

He said the law, in part, was what had prompted accountants to engage in the kind of questionable practices that have undone companies such as Enron Corp.

"You're not allowed to do any discovery request for internal documents‚ so to a great extent you are dependent on employees and former employees to come forward with information," Federman said.

"The way Congress has rigged it, the defendant needs to self-disclose."

The Securities and Exchange Commission is separately investigating whether Halliburton's accounting change was appropriate and justified and whether it was disclosed in a timely manner.