Let's see what real lawyers have to say on this matter .
Sorry But Jeff Sessions Absolutely Did NOT Perjure Himself Under Oath When Asked About Russia
The criminal law only prohibits lying to Congress under two statutes — 18 USC 1621 and 18 USC 1001.
Section 1621 requires a person “willfully and contrary” to a sworn oath “subscribe a material matter” which is both false and the person knows to be false.
Section 1001 is basically the same, without certain tribunal prerequisites: it also requires the government prove a person willfully made a materially false statement.
This requires three elements: first, a false statement; second, the false statement be “material”; and third, the false statement be made “knowingly” and “willfully.”
A statement is not false if it can be interpreted in an innocent manner.
A statement is not material if it is not particularly relevant to the subject of the inquiry.
Willfully is a very high standard of proof: it requires the person know they are committing the crime, and do so anyway.
None of the three exist as to Sessions.