“I have to ask our witnesses, what were you thinking?” said Representative John D. Dingell, Democrat of Michigan, who called the effort “a plumbers’ operation that would make Richard Nixon blush were he still alive.”  In a hearing that stretched from 10 a.m. to 6 p.m. with only a half-hour break, the legislators grilled Ms. Dunn over her responsibility for the investigation and her awareness of the methods, with only a few questions aimed at her fellow panel members. Mr. Hurd later testified alone.  The scene was remarkable for the gathering of so many officials of one company in a Congressional hearing room — at the behest of the Energy and Commerce investigations subcommittee, which once looked into quite different corporate scandals at Enron and WorldCom.  Before lawmakers got any answers, they had to dispense with a group of 10 recalcitrant witnesses, including three officials who have left the company and several of the investigators they employed. One by one, they declined to answer the committee’s questions, invoking their Fifth Amendment right against self-incrimination.  They included the company’s general counsel, Ann O. Baskins, whose lawyers announced early Thursday that she had resigned, while insisting that she had been repeatedly assured by subordinates that the operation was legal.  But the committee also released handwritten notes Ms. Baskins took in a meeting on June 15, 2005, that showed she was aware of the use of “pretexts to extract info.”  It is the use of pretexting — obtaining another person’s phone records through a ruse — that was the ostensible interest of the panel, which put forward legislation earlier this year to outlaw the practice. But as the day’s hearing went on, the lawmakers’ indignation extended to the investigators’ whole bag of tricks.  Ms. Dunn provoked the most disbelief with her insistence that she did not supervise the investigation and that she believed that private phone records could be obtained legally. At one point, she said she believed until six months ago that one could simply call the phone company and obtain another person’s records.  “You really believe that? You honestly believed that it was that simple?” asked Representative Greg Walden, Republican of Oregon.  Ms. Dunn was also questioned about her blessing of a plan to send a misleading e-mail message to a reporter, along with tracer software that would let H.P. detectives know to whom the document was forwarded.  Reading from a document, Representative Diana DeGette, Democrat of Colorado, noted that Ms. Dunn had said the plan was “clever” and should be sent to Mr. Hurd for approval.  “I regret the use of the word ‘clever,’ ” Ms. Dunn said.  “I’m sure,” Ms. DeGette replied.  By way of defending her actions — or rather, inaction — Ms. Dunn responded that it was not her role to approve investigative techniques.  “This is a very serious problem,” Ms. DeGette said. “You can’t say, ‘I’m just a board member, but I’m not responsible for things that happen because I am not in the chain of command.’ ”  Ms. Dunn was repeatedly confronted with documents showing that Ronald R. DeLia, the outside investigator employed by H.P. and one of the witnesses who refused to testify, contended that she was aware of pretexting early in the investigation.  “I have no recollection of a conversation with Mr. DeLia that included the word ‘pretexting,’ ” Ms. Dunn replied at one point. She later added, “I don’t agree with Mr. DeLia’s testimony.”  Her main expression of remorse was in her opening statement when she said, “I deeply regret that so many people, including me, were badly let down by this reliance” on the expertise of others.  Questions for Mr. Hurd were rarely as tough. Representative Michael C. Burgess, Republican of Texas, asked him if he could restore integrity to Hewlett-Packard. Mr. Hurd pointedly removed his glasses and said, “I will.”  It was an artful performance by Mr. Hurd, who acknowledged, as he had previously, that he was at two meetings where the operation was discussed. He said he did not pay attention because the investigation was not as high a priority as running the company. “I pick my spots where I dive into details,” he said.  He also said he had approved sending an e-mail message with bogus information intended to smoke out a leaker, but said he had not approved adding tracer software.  Mr. Hurd was asked several times about the software’s use. He did not say that the company would stop using it, only that it would investigate whether it should. Fred Adler, an investigator also called as a witness, said Hewlett-Packard had used it recently at least two dozen times.  Several members acknowledged that the panel had gone easier on Mr. Hurd than on Ms. Dunn. “We didn’t have the documents on him that we had on her,” Edward Whitfield, the subcommittee chairman, said later.  He said that Mr. Hurd’s acceptance of responsibility also played a part in the way they questioned the two executives. Mr. Whitfield said with Ms. Dunn’s extensive background in business and finance, he expected more sophisticated answers. “She portrayed herself as so far removed,” he said.  And few people think Mr. Hurd is in any trouble with H.P.’s shareholders or its board. On Wednesday, Robert Ryan, a board member, was calling reporters — with the company’s authorization — to express his and the board’s support for Mr. Hurd, who has presided over a resurgence of Hewlett-Packard’s business.  Investors appeared to agree, with Hewlett-Packard’s stock rising 1.6 percent in regular trading and 1.5 percent more after hours, when Mr. Hurd made his appearance.  Charles R. Wolf, a computer industry analyst with Needham & Company, said the strong stock performance and Mr. Hurd’s popularity among employees would make it difficult for the board to remove him.  “I’d say the likelihood of his being forced to resign over this is close to zero,” he said. “He’s done such a terrific job managing this company for the past year and a half, it would take a bulldozer to get rid of him.”  Before Mr. Hurd’s appearance, the company’s outside counsel, Larry W. Sonsini, whom many consider the most influential lawyer in Silicon Valley, appeared on the panel with Ms. Dunn.  He, too, was able to deflect much of the lawmakers’ ire.  Mr. Sonsini said several times that a statement he had made in an e-mail message in June that the investigation appeared to be “within legal limits” had been misinterpreted. He said it did not amount to a legal opinion, but rather a statement reflecting what he was told by Kevin T. Hunsaker, the senior lawyer who led the investigation, and Ms. Baskins.  It was only later, after Hewlett-Packard asked his firm to investigate the investigation, that he fully understood the methods employed by Hewlett-Packard and concluded that “they are totally improper.”  Lawmakers convened the hearing, in part, to emphasize the need for legislation that explicitly bans the use of pretexting to obtain phone records.  The committee approved a bill to that effect earlier this year, but it has yet to be taken up by the full House of Representatives.  In one of the few lighthearted exchanges, Representative Joe Barton, Republican of Texas and chairman of the full committee, told Ms. Dunn, “If I called you up, Ms. Dunn, and asked you for your phone records for the last six months, would you give me that?”  “In your position,” Ms. Dunn said, then added after a pause, “I would give you my phone records.”  The room exploded with laughter, and Mr. Barton replied, “Well, praise the Lord, I wouldn’t give you mine.”  Jeremy W. Peters contributed reporting from New York.  A version of this article appears in print on , on Page C1 of the New York edition with the headline: H.P. Before a Skeptical Congress. Order Reprints| Today's Paper|Subscribe
Hewlett-Packard’s top executives tried to explain why they did not question the legality of an internal spying operation.