A divided U.S. Federal Communications Commission adopted Internet traffic rules, provoking warnings they would be rejected in the courts and threats from Republican lawmakers to overturn them.

The rules highlight a huge divide between those who say the Internet should be allowed to flourish without regulation and those who say the power of big high-speed Internet providers like Comcast Corp. to discriminate against other players needs to be restrained.

Under the rules, the blocking of legal content would be banned but providers like Comcast and Verizon Communications can "reasonably" manage their networks and charge consumers based on levels of Internet usage.

Wireless carriers like Sprint Nextel and Deutsche Telekom AG T-Mobile would get slightly more discretion to manage their networks but could not block access to websites, or to competing voice and video applications.

The rules are expected to go into effect early next year but FCC Chairman Julius Genachowski said consumers should expect few changes. "In many respects, this is about preserving the freedom and openness of the Internet that has worked for many years," he said.

Experts say legal challenges could tie the rules up for years. "A definitive judicial resolution is still three to five years down the road," predicted Michael Botein of New York Law School.

Approved by Genachowski and his two fellow Democrats, the rules were quickly condemned by Republicans, and some companies, as excessive and unnecessary.

"Litigation will supplant innovation. Instead of investing in tomorrow's technologies, precious capital will be diverted to pay lawyers' fees," FCC Commissioner Robert McDowell warned.