What are the repercussions of lying under oath? Are they different in a deposition then in court? Do they vary state to state?

Perjury:

“Criminal offense of making false statements under oath. In Common Law, only a willful and corrupt sworn statement made without sincere belief in its truth, and made in a judicial proceeding regarding a material matter, was perjury. Today, Statutes have broadened the offense so that in some Jurisdictions any false swearing in a legal instrument or legal setting is perjury.”

I wouldn’t risk it…

It’s called purgery.

Remember our buddy Bill Clinton? “I did NOT have sex with Monica Lewinsky.” That is purgery and that is why he got in trouble.

Don’t lie. If you don’t want to answer take the fifth or state “To the BEST of my knowledge”

Thanks, people, but my question is being asked academically.

Purgery sounds like making oneself or someone else throw up.

Perjury, as bythebay said, is a criminal offense. From CriminalDefenseLawyer:

“When facing a subpoena to testify in a court of law, individuals issuing false statement under oath or affirmation face perjury penalty charges and crimes. Many individuals highly underestimate the potential damage a perjury conviction can bring to themselves and others. In fact, according to Federal prosecutors in 2008, the perjury penalty for convicted persons is up to five years in prison. State and local court cases also offer similarly staunch penalties for those attempting to subvert the sanctity of the courts.”

Emphasis mine.

Ah, perjury. Every jurisdiction on earth may have different penalties, but they all have a penalty for lying under oath. Don’t lie in court! Not even in a deposition!

and other bad things will happen to you, eg you won’t be able to enjoy sex ever again and you’ll lose your wallet and get cancer