Russian Parliament Expels Gennadi V. Gudkov, a Putin Opponent MOSCOW - Russia's Parliament on Friday took the rare step of expelling one of its members, a veteran lawmaker and former K.G.B. officer who last year crossed a political line in the sand when he joined crowds calling for the ouster of President Vladimir V. Putin. The legislator, Gennadi V. Gudkov, was stripped of his mandate because he was accused of operating a business while holding office, which violates Russian law. The political context, however, left little doubt that the move was driven by Mr. Gudkov's support for the opposition and his role as a link between street activists and dissenters within the government. Though Russian authorities have brought charges against many political activists this summer, Mr. Gudkov, 56, is the first insider to be sanctioned in this way. A blustery, rumpled populist in the vein of Boris N. Yeltsin, the former president, he used his last moments on the floor of the Duma to address Mr. Putin. "Why is the most important person in the state, the president and guarantor of the Constitution, silent today?" he asked. Does he approve of what is going on at the Duma? Does he understand what a dangerous precedent the country is creating? Does he understand what a dangerous Pandora's box we are opening here, now, on the 14th of September of this year? And if he keeps silent? Mr. Gudkov said. That means he approves of it. The last time the Parliament voted to expel one of its members was in 1995, against Sergei Mavrodi, the founder of a notorious pyramid scheme that bankrupted vast numbers of investors. In 2010, when Ashot Egiazaryan was accused of embezzling $87 million from a construction project, the Duma voted to strip him of his immunity from prosecution, but to preserve his mandate (and his salary). Within hours of the Duma's vote on Friday, a spokesman for Russia's Investigative Committee said the authorities were considering opening a criminal case against Mr. Gudkov, who no longer has immunity. The spokesman, Vladimir Markin, said a final decision would be made in the next two weeks. Mr. Gudkov has denied violating the law, which allows lawmakers to earn money from family businesses but not to serve in a management capacity. The move will serve as a stern warning to other members of Parliament, which has been relatively docile over the 12 years since Mr. Putin first came to power. That seemed to end during the run-up to parliamentary elections in December, when Mr. Gudkov delivered a fiery speech warning United Russia, the ruling party, that vote-rigging might alienate voters and the so-called "systemic opposition," which represents leftist and nationalist minorities in Parliament. "Even a hare, when driven into a corner, will turn into a beast," he said. Indeed, over the next several months, A Just Russia - the left-leaning party Mr. Gudkov belongs to - became increasingly assertive, with some members showing up for hearings wearing the white ribbons that are the symbol of the protests that began in December. In June, when United Russia rushed through a law imposing harsh penalties on people who participate in unauthorized rallies, members of the party tried to block it by means of a so-called "Italian strike," a sort of filibuster. Mr. Gudkov's punishment may also exacerbate a split in the Russian elite, however, by highlighting increased vulnerability to accusations of corruption. Many of 450 deputies in the Duma have vast personal wealth they could not possibly have accumulated on their five-figure government salaries, but have never faced sanctions or even the threat of them. As lawmakers filtered out after of the vote on Friday afternoon, Mr. Gudkov's allies said they would devote new energy to publicizing the wealth of loyalist lawmakers and pushing for them to be held to the same standard as Mr. Gudkov. "From now on, the situation of mutual blames, showdowns, and insinuations will be endless," wrote Ilya V. Ponomarev, a two-term deputy with A Just Russia, in a blog post shortly after the vote. There will be purges, mutual surveillance, suspicions; and constructive approach to work will fall to zero. The only way out of this situation is the dissolution of the Duma.