A U.S. senator has blocked a controversial bill that would enlist ISPs, search engines and other businesses in blocking access to alleged websites infringing copyright.

Senator Ron Wyden, an Oregon Democrat, has blocked the Preventing Real Online Threats to Economic Creativity and Theft of Intellectual Property Act, or PROTECT IP Act, from coming to the Senate floor for a vote.

On Thursday, just two weeks after the bill was introduced, the Senate Judiciary Committee unanimously voted to move the PROTECT IP Act to the Senate floor. Under Senate rules, a single senator can place a hold on a bill, although the block can be overridden by a 60-vote majority.

The PROTECT IP Act would allow the U.S. Department of Justice to seek court orders requiring search engines and ISPs to stop sending traffic to websites accused of infringing copyright. The bill would also allow copyright holders to seek court orders requiring payment processors and online ad networks to stop doing business with allegedly infringing websites.

The legislation would attack free speech online and hurt e-commerce, Wyden said.

"I understand and agree with the goal of the legislation, to protect intellectual property and combat commerce in counterfeit goods, but I am not willing to muzzle speech and stifle innovation and economic growth to achieve this objective," he said in a statement. "At the expense of legitimate commerce, [the bill's] prescription takes an overreaching approach to policing the Internet when a more balanced and targeted approach would be more effective. The collateral damage of this approach is speech, innovation and the very integrity of the Internet."

Wyden called the Internet the "shipping lane" of the 21st century. "It is increasingly in America's economic interest to ensure that the Internet is a viable means for American innovation, commerce, and the advancement of our ideals that empower people all around the world," he said. "By ceding control of the Internet to corporations through a private right of action, and to government agencies that do not sufficiently understand and value the Internet, [the bill] represents a threat to our economic future and to our international objectives."

Critics of the bill have said it would lead to hundreds of court cases brought by copyright owners against online businesses. The legislation would lead to a blacklist of Internet sites and compromise the Internet's Domain Name System, critics have said.

But backers of the bill have said new methods are needed to combat copyright infringement by foreign websites. The bill would target the worst foreign websites trafficking in digital piracy and counterfeit goods and would dry up their business by focusing on user traffic, advertising and payments, proponents said.

"Copyright infringement and the sale of counterfeit goods can cost American businesses billions of dollars, and result in hundreds of thousands of lost jobs," Senator Patrick Leahy, a Vermont Democrat and lead sponsor of the bill, said Thursday.

U.S. law enforcement agencies are limited in their ability to combat infringing websites operated overseas, Leahy added in a statement. "American consumers are too often deceived into thinking the products they are purchasing at these websites are legitimate because they are easily accessed through their home's Internet service provider, found through well known search engines, and are complete with corporate advertising, credit card acceptance, and advertising links that make them appear legitimate," he said.

Wyden blocked a similar bill, the Combating Online Infringement and Counterfeits Act, or COICA, after the Senate Judiciary Committee passed it in late 2010. COICA would have expanded federal agencies' power to seize the domain names of allegedly infringing websites.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is grant_gross@idg.com.