The Republican chairman walked off with the gavel, leaving Democrats shouting into turned-off microphones at a raucous hearing Friday on the Patriot Act (search).

The House Judiciary Committee hearing, with the two sides accusing each other of being irresponsible and undemocratic, came as President Bush was urging Congress to renew those sections of the post-Sept. 11 counterterrorism law set to expire in September.

Rep. James Sensenbrenner (search), R-Wis., chairman of the panel, abruptly gaveled the meeting to an end and walked out, followed by other Republicans. Sensenbrenner declared that much of the testimony, which veered into debate over the detainees at Guantanamo Bay (search), was irrelevant.

Rep. Jerrold Nadler, D-N.Y., protested, raising his voice as his microphone went off, came back on, and went off again.

"We are not besmirching the honor of the United States, we are trying to uphold it," he said.

Democrats asked for the hearing, the 11th the committee has held on the act since April, saying past hearings had been too slanted toward witnesses who supported the law. The four witnesses were from groups, including Amnesty International USA (search) and the American Immigration Lawyers Association, that have questioned the constitutionality of some aspects of the act, which allows law enforcement greater authority to investigate suspected terrorists.

Nadler said Sensenbrenner, one of the authors of the Patriot Act, was "rather rude, cutting everybody off in mid-sentence with an attitude of total hostility."

Tempers flared when Rep. Mike Pence, R-Ind., accused Amnesty International of endangering the lives of Americans in uniform by referring to the prison at Guantanamo Bay as a "gulag." Sensenbrenner didn't allow the Amnesty representative, Chip Pitts, to respond until Nadler raised a "point of decency."

Sensenbrenner's spokesman, Jeff Lungren, said the hearing had lasted two hours and "the chairman was very accommodating, giving members extra time."

James Zogby, president of the Arab American Institute, speaking immediately after Sensenbrenner left, voiced dismay over the proceedings. "I'm troubled about what kind of lesson this gives" to the rest of the world, he told the Democrats remaining in the room.

House Democratic leader Nancy Pelosi, in a statement, said the hearing was an example of Republican abuse of power and she would ask House Speaker Dennis Hastert to order an apology from Sensenbrenner.