Helix editor?! When?! Now in Helix Posted February 29, 2016 I deal with NDA's for a living. Breaking one is NOT illegal; it is breach of contract and opens one up to liability from termination to litigation. Nobody goes to jail for breaking an NDA unless they are under contract with a governmental entity and subject to criminal prosecution (ie treason or espionage). HOWEVER, if one is licensed by the government and said liscensee breaks a fiduciary commitment (ie insider trading, violation of code of conduct, etc) then they can face punitive damages and possible criminal prosecution. The term legal/illegal does not apply exclusively to criminal law. Breaching a contract is illegal. Like all things in law, it is up for debate.