Updated at 11 a.m. ET
Beginning this week, members of Congress intend to get answers from the National Security Agency about the legal justification it's been relying on for its sweeping surveillance activities. Congress will get its chance to question the intelligence community with a series of briefings and at least two hearings this week, while a few members will meet Tuesday to consider a possible lawsuit in response to the surveillance revelations.
"I think it's a constitutional issue, without a doubt," Rep. Thomas Massie, R-Ky., said to CBSNews.com about the NSA's recently revealed tactics, which include the widespread collection of U.S. phone records from Verizon, as well as the collection of internet content from non-U.S. internet users outside of the United States. While the collection of internet content doesn't target U.S. users, the NSA could capture information from Americans unintentionally.
"I don't think the Constitution allows for broad sweeps of personal data of people who aren't even suspected of doing anything," Massie said. "As of this week, we now know that's occurring."
Massie said he's meeting Tuesday with Rep. Justin Amash, R-Mich., and Sen. Rand Paul, R-Ky. -- two other civil liberties advocates -- to discuss a possible lawsuit on the matter, though he declined to go into more detail.
On Fox News Sunday over the weekend, Paul said, "I'm going to be seeing if I can challenge this at the Supreme Court level. I'm going to be asking all the internet providers and all of the phone companies: Ask your customers to join me in a class action lawsuit. If we get 10 million Americans saying we don't want our phone records looked at, then maybe someone will wake up and something will change in Washington."
While the breadth of the NSA's surveillance is broad -- and some say unconstitutional -- many lawmakers and experts say it has a basis in the sweeping surveillance measures passed by Congress in the Patriot Act and 2008 FISA Amendments Act (which amended the Foreign Intelligence Surveillance Act).
The FISA Amendments Act was challenged in the Supreme Court as recently as last year in Clapper v. Amnesty International USA. In that case, plaintiffs including lawyers and journalists sued, arguing their communications with foreign contacts were targeted by the U.S. government. In its ruling this year, the court essentially punted on the case, arguing the plaintiffs had no standing (in other words, that the plaintiffs had no proof that they were either the targets of surveillance or would be in the future).
Clapper was a serious blow to privacy advocates, but with the new revelations of government surveillance, "the landscape for standing... has changed significantly," Loyola Law School professor Karl Manheim, an expert on constitutional law and privacy, told CBSNews.com.
"Ordinarily, a lower court would be bound by the Clapper decision and the case would be dismissed," he said. However, "since there doesn't seem to be any lack of people who have been injured by these programs, a different set of plaintiffs could sue."
While a court challenge may or may not be in the future, members of Congress are at least looking for a fuller explanation of the NSA's interpretation of the Patriot Act and the FISA Amendments Act.
The full House of Representatives will get an NSA briefing Tuesday afternoon, while the House Intelligence Committee will get another briefing on Thursday. The Senate Intelligence Committee will hold another briefing on details of the NSA programs, open to all members of the U.S. Senate, on Thursday.