When the Enron Corp. scandal broke in late 2001, the U.S. attorney's office in Houston had to step aside from the investigation because so many of its lawyers had spouses and other relatives with close ties to the failed energy giant.

So officials in the Justice Department reached for an unusual solution: creating a task force of experienced prosecutors and FBI agents from around the nation whose mission was to get to the root of what happened at Enron.

For 21/2 years, the Enron task force worked its way through the company's chain of command, bringing criminal charges against 30 people. Thursday it added one more: former chief executive Kenneth L. Lay.

Typically, the Justice Department has employed task forces to root out fraud across an industry or to explore a significant issue. For instance, government officials established a campaign finance task force less than a decade ago to probe improper political donations. Exploring a particular company is more rare.

While the government considers the Enron task force a huge success, defense lawyers who represent prominent targets in the probe strongly disagree. They argue that such an investigatory model puts immense pressure on government lawyers to pursue corporate titans to advance their careers. In essence, detractors say, a task force can pick targets and then find crimes for which to bring charges.

"It's the nature of a special prosecutor's office" to go after the highest possible target, said Michael Ramsey, Lay's defense lawyer, before the indictment was unsealed this week. "That as a structural thing troubles me."

Daniel M. Petrocelli, the lead trial counsel for Lay's protege Jeffrey K. Skilling, who is facing numerous fraud and insider-trading charges himself, agreed.

"The task force attempt to lay blame on people like Ken Lay and Jeff Skilling for the acts of a few is reckless and irresponsible," Petrocelli said Thursday. "This has got to stop, and hopefully a jury will put an end to it."

Robert S. Bennett, a longtime defense lawyer and former prosecutor, said having a U.S. attorney's office investigate a prominent case generally offers an extra layer of protection from such criticisms.

"If people have lots of different cases, there's a safety valve in the system, so that no one case becomes too important," he said.

Bennett, who represents Enron, hastened to add that he believes government lawyers have acted professionally and fairly throughout the probe.

But Eric H. Holder Jr., a deputy attorney general during the Clinton administration, said the Enron prosecution model makes sense, "given the complicated nature of the alleged crimes and the nationwide scope of the fraud."

Holder said the two directors of the task force, first Leslie R. Caldwell and now Andrew Weissmann, are career prosecutors experienced in rooting out white-collar schemes and insulated from political pressure.

Added Houston lawyer Philip H. Hilder, who is representing several witnesses in the Enron investigation: "Frankly I don't see how else it could have worked. . . . I think the response was unprecedented but appropriate."

Government officials say the proof is in the record amassed by the task force, which encompasses 22 FBI agents, 15 prosecutors, two Internal Revenue Service agents and 10 support staffers. About 20 more lawyers, accountants and paralegals at the Securities and Exchange Commission work alongside prosecutors to investigate Enron. So far, the government has collected $430 million in financial penalties that will eventually be returned to shareholders.