While the press and public may have been denied a dramatic raise-your-right-hand moment in Congress this week, Facebook’s chief executive is still under legal obligation to tell the truth.

If it feels like Zuckerberg is bending the truth, know that making a false statement to Congress might be difficult to prove given the slippery nature of congressional testimony, but it’s still illegal.

Since some corners of the internet appear to be floating a conspiracy theory that Zuckerberg can get away with lying because he did not take the oath, we clarified that point with the offices of some of the committee members questioning him.

“Lying to Congress is always a crime,” a representative for Senator Dianne Feinstein clarified to TechCrunch. “You don’t need to be sworn in.”

A witness who is not under oath cannot face perjury charges but they could face charges pertaining to making “false statements,” a broader statute that is not specific to lying under oath.

As Lawfare clarifies:

By far the broadest federal statute criminalizing lying is 18 U.S.C. § 1001, which makes it a crime to “knowingly and willfully . . . make[] any materially false, fictitious, or fraudulent statement or representation” in the course of “any matter within the jurisdiction of the executive, legislative, or judicial branch” of the federal government. There’s no requirement that the statement be under oath.

Committees handle the matter of swearing-in a witness a number of different ways, and there are three committees involved in Zuckerberg’s testimony this week: the Senate Committee on the Judiciary, the Senate Committee on Commerce, Science, and Transportation and the House Energy and Commerce Committee. The Senate committees banded together to form a joint hearing on Tuesday.

As a Republican Commerce committee aide told CNN, “By tradition, the Commerce Committee does not swear-in witnesses.”

As Slate reported in a piece exploring the tradition of the oath, “the judiciary committee requires an oath only sometimes, according to the procedural guidelines of the Senate select committee on ethics.” Where it is not required, the decision to require the oath can be made at the discretion of the committee chairman and that decision takes place during the hearing’s planning stage.

“Witnesses aren’t always sworn in before voluntarily providing testimony,” Chuck Grassley’s Senate Judiciary Committee press secretary told TechCrunch.

Still, it isn’t exactly random. It’s possible that Facebook stipulated that Zuckerberg not be made to take the oath as a condition of his appearance before Congress. The optics of Facebook’s founder with his right hand raised would likely be anathema to the feverishly PR-conscious company.

An aide to a prominent Senator not questioning Zuckerberg this week confirmed to TechCrunch that such a negotiation would be unusual but not impossible. Facebook did not respond to our questions on the topic.

While no one can legally outright lie in responding to Congress — under oath or not — witnesses go to great lengths to temper their speech so they don’t get into hot water. During his first Congressional testimony, Zuckerberg spoke in an extremely disciplined, well-practiced way that adhered closely to safe talking points established in advance.

A number of Zuckerberg’s statements could certainly be interpreted as lying by omission in an informal sense, but legally his testimony remains strategically vague enough to stay well within legal bounds.