Judge Andrew Napolitano stopped by Fox Business Network's Varney & Co. to weigh in on President Obama signing a five-year extension of the government's warrantless wiretapping program. In doing so, the judge said Obama is continuing with a practice that is "absolutely unconstitutional" and a violation of the Fourth Amendment's protection against unreasonable search and seizure.

Napolitano explained that the government can listen to any phone call or read any email from a person in the United States to a person outside the country even without a search warrant.

Varney asked what justification the government has for this practice.

More From Judge Napolitano on Privacy Issues:

"[It is] an absurd, nativist, racist belief that Americans who deal with foreigners are more likely to be a danger to the security of the country than Americans who don't deal with foreigners. That's preposterous," said Napolitano.

That prompted Varney to ask whether this type of eavesdropping has yielded information that ultimately stopped a terror attack.

"The government will say 'yes' but it won't produce the evidence because it claims it's secret. So you believe it if you want. ... I don't believe it at all. And if it were so, it would violate your Fourth Amendment privilege to be free from unreasonable search and seizure," said Napolitano.

Watch the full discussion:

Follow Fox News Insider, the official blog of Fox News Channel on Twitter and Google+!