When Facebook CEO Mark Zuckerberg takes the stand before a joint congressional panel on Tuesday, he will not be under oath, Breitbart News has learned. But he will be required by federal statute to tell the truth, and if he lies he could face serious legal consequences.

A senior Senate GOP aide helping organize the joint Senate Judiciary Committee and Senate Commerce Committee hearing told Breitbart News that it is standard practice not to swear witnesses like this in under oath. But they are required by law to tell the truth, the aide says.

“He won’t be under oath, but he is under legal obligation to tell the truth,” the Senate aide told Breitbart News of Zuckerberg.

The Senate hearing, the first of two appearances Zuckerberg will make before Congress this week, begins at 2:15 p.m. ET on Capitol Hill. Judiciary Committee chairman Sen. Chuck Grassley (R-IA) will begin by explaining how the joint committee hearing will operate, then opening statements will be made by Senate Commerce Committee chairman Sen. John Thune (R-SD), Judiciary Committee Ranking Member Sen. Dianne Feinstein (D-CA), Grassley, and Commerce Committee ranking member Sen. Bill Nelson (D-FL).

Zuckerberg himself will deliver a five-minute statement as well; then the hearing will be open to committee members for questioning the highly controversial Facebook CEO and founder.

Between the two committees, a whopping 44 senators will have the opportunity to question Zuckerberg on Tuesday afternoon.

This is just the first of two official testimony appearances Zuckerberg will make on Capitol Hill this week. After the Senate hearing on Tuesday, Zuckerberg will return to the Capitol on Wednesday for another hearing on the other side of Capitol Hill before the House Commtitee on Energy and Commerce.