A bill giving the president an Internet "kill switch" during times of emergency that failed to pass Congress last year will return this year, but with a revision that has many civil liberties advocates concerned: It will give the president the ability to shut down parts of the Internet without any court oversight.

The Protecting Cyberspace as a National Asset Act was introduced last year by Sens. Joe Lieberman (I-CT) and Susan Collins (R-ME) in an effort to combat cyber-crime and the threat of online warfare and terrorism.

Critics said the bill would allow the president to disconnect Internet networks and force private websites to comply with broad cybersecurity measures. Future US presidents would have those powers renewed indefinitely.

According to a report Monday at CNET News, the bill will be back on the Senate agenda in the new year. But a revision introduced into the bill in December would exempt the law from judicial oversight. According to critics, this change would open the law to politically-motivated abuse by any administration, no matter how narrowly the law is interpreted.

"The country we're seeking to protect is a country that respects the right of any individual to have their day in court," Steve DelBianco, director of the NetChoice coalition, which represents online companies such as eBay and Yahoo, told CNET. "Yet this bill would deny that day in court to the owner of infrastructure."

"Judicial review is our main concern," he added. "A designation of critical information infrastructure brings with it huge obligations for upgrades and compliance."

Under the proposed law, the Department of Homeland Security would draw up a list of Internet "critical infrastructure" it deems vital to the proper functioning of the web and US economy. The president would then be granted the power to order some part of that critical infrastructure to be shut down, in case of a "national cybermergency."

While the bill does lay down what constitutes "critical infrastructure," critics say it's not clear what constitutes a "national cyberemergency." Nor is it clear what other powers the president may exert, aside from shutting down parts of the web.

For instance, some observers wonder whether the president would be able to order Internet service providers to hand over information about customers, or their activities online, during a "national cyberemergency." As a result, the ability of online companies to appeal only to the DHS secretary -- and not the courts -- has many civil libertarians alarmed.

"No amount of tightening of what constitutes 'critical infrastructure' will prevent abuse without meaningful judicial review," Berin Szoka, an analyst at the TechFreedom think tank, told CNET. "Blocking judicial review of this key question essentially says that the rule of law goes out the window if and when a major crisis occurs."

Backers of the bill have argued that it doesn't constitute a "kill switch" for the Internet -- and even if it did, it doesn't matter because the president already has the power to shut down communications networks during times of war.

But critics argue that if the law really changed nothing, it wouldn't be necessary. And they point out that the Communications Act of 1934 only gives the president the ability to shut down communications during times of war, whereas the proposed bill would allow it during times of "national cybermergency," a concept evidently left to the president to define.

The Protecting Cyberspace as a National Asset Act is by no means the only proposal seeking to grant government more control over the Internet. The Combating Online Infringement and Counterfeits Act, proposed in Congress last year, would give the federal government the power to shut down any domain deemed to be engaged in copyright violations.

Critics said the bill is both a giveaway to the movie and recording industries and a step towards widespread and unaccountable censorship of the Internet.

Oregon Democratic Sen. Ron Wyden placed a hold on that bill last year, effectively killing it in the last congressional session, but many observers expect the bill to make a comeback this year.