Peterson on Death Row for murdering his wife, Laci. Phone taps are also a major weapon in the war on terror.

Whatever the crime, law enforcement is seeking more and more warrants to listen in -- 1,800 federal warrants last year, and thousands more at the local level.

Charles Cullen, Palo Alto Police Dept.: "We don't have the resources to keep up with all of the emerging technology, and as you know, it changes every day."

Rather than try to keep up with new technology, the FBI and Justice Department convinced Congress to pass a law in 1994 called CALEA -- the Communications Assistance for Law Enforcement Act. It says phone companies have to configure their systems so police can easily tap in, even if that police technology is 15 years old, and it often is.

But the law seemed to exempt phone calls made over the Internet.

Lee Tien, Electronic Frontier Foundation: "At least that's what most people thought."

Not the FBI or Justice Department. In 2004, they convinced the FCC to expand the law to cover Voice over Internet Protocol or VoIP calls.

Lee Tien: "Every privacy group was against it because we thought there were major problems there, but we lost."

Now VoIP providers find themselves hurtling toward an expensive deadline to install hardware that will keep hackers out, but let law enforcement in.

Bryan Martin, 8x8 CEO: "We're being required by the FCC to implement CALEA by May 14th this year. That costs us money to do that and frankly kind of slows down the development of Voice over IP."

8x8 Communications is based in Santa Clara and provides Voice over Internet telephone and picture phone services. CEO Bryan Martin says making the required changes will be expensive and customers will inevitably foot the bill.

That's one of the few things everyone agrees on when it comes to CALEA. There are disagreements about privacy. Law enforcement and phone companies say they can tap into the intricate information structure of the Web without violating the privacy of other phone customers. Privacy groups disagree.

Lee Tien: "With the Internet phone or Internet communications it's much harder to isolate one particular communication because they're all traveling like water through pipes and everyone's calls are mixed together."

Charles Cullen: "That certainly is a concern for the citizens, but I think there is a way to work through that and get what law enforcement needs and still maintain privacy of the citizen."

A big limitation of CALEA is that currently it only allows law enforcement to intercept audio, not video, so a determined terrorist could use sign language. Even that may not be true for long. There's no question that phone taps are a necessary law enforcement tool, but the Voice over IP requirements are so new that many provisions aren't clear, and may have to be hammered out in court.