It was impossible for him to do so because he was never testifying under oath.

See: <https://www.c-span.org/video/?311436-1/senate-intelligence-c...> for a recording of what I believe is the Senate hearing to which you are referring.

Also consider the following quote from the Congressional Research Service about how the Senate chooses to place folks under oath:

> By statute, any Senator is authorized to administer the oath to a witness (2 U.S.C. 191). Committee rules commonly allow testimony under oath at the discretion of a committee’s leaders. (In practice, most committees rarely require witnesses to testify under oath at legislative hearings. Sworn testimony is more common at investigative hearings and confirmation hearings.)

(via: <https://crsreports.congress.gov/product/pdf/RS/98-392>)

Now, the NSA's lawyers absolutely _did_ lie under oath to the Supreme Court.

What happened because of that? Absolutely fuckall.

So, even if Clapper was testifying under oath, I'd expect absolutely nothing would have happened. (Don't forget that this is mostly the same Congress that gave every telecom company that (very, _very_ much illegally) permitted NSA warrantless access to their phone and data networks _retroactive_ immunity from prosecution.)