Judge Andrew Napolitano and Stuart Varney had a lively debate (video above) on FBN this morning after the NSA's bulk collection of phone records was found to be illegal. 

A federal appeals court ruled that the NSA cannot collect the phone records of millions of Americans under the current version of the Patriot Act.

The Wall Street Journal reports:

The NSA has used the Patriot Act to justify collecting records of nearly every call made in the U.S. and entering them into a database to search for possible contacts among terrorism suspects.

The scope of the program was revealed when former NSA contractor Edward Snowden leaked documents describing the program, triggering a national debate over the extent of the data collection.

The ruling by the three-judge panel in New York comes at a delicate point in the national debate over government surveillance, as Section 215 of the Patriot Act is due to expire next month and lawmakers are haggling about whether to renew it, modify it, or let it lapse.

Varney asked the judge whether authorities would be able to go back and look at illegally-obtained data in the event of a terrorist attack. 

Napolitano said that probably would not be legal, but added that the NSA would likely do it anyway in that situation. 

"I would say do it and you would not," Varney said. 

Napolitano explained that "federal spies" failed to stop the two gunmen that attacked a Muhammad cartoon contest in Garland, Texas, last weekend. 

He argued that the government is missing suspects because it's collecting far too much unnecessary information.

"It's a failure of principle because it gives the NSA too much to go through. The Constitution limits them to probable cause. If they followed the Constitution, they would only be going after the bad guys," said Napolitano. 

He said the broad surveillance tactics are "blatantly unconstitutional," and even if Congress would like to, they "cannot change the Constitution."

Watch the debate above.

Napolitano also reacted on "America's Newsroom," explaining that it's now up to Congress to decide whether to allow the massive surveillance to continue. 

The court is not blocking the program, instead letting Congress take action one way or the other on renewing or modifying the Patriot Act.

"Congress must move by the end of May or this law expires and the NSA spying will stop dead in its tracks," Napolitano said.

There could now be an appeal of this particular ruling, which would then take the case to the Supreme Court. 

Napolitano said that right now, the law doesn't allow bulk collection without an individual warrant.

He recalled that in the weeks after the 9/11 attacks, the Bush administration allowed the spying to be conducted based on a provision of the Patriot Act. 

"Without anybody knowing it, President Bush took a clause of the Patriot Act, had his lawyers give an interpretation to it that said, 'the NSA can listen in on every phone call, and read every text message and every email.' Fast-forward to today and a federal appeals court in New York City ruled that's an improper interpretation of the act. Congress never authorized it. The NSA spying is illegal," the judge said.

Watch Judge Napolitano's analysis on "America's Newsroom" below.