De jure (in Classical Latin de iure) is an expression that means "concerning law", as contrasted with de facto , which means "concerning fact". The terms de jure and de facto are used instead of "in law" and "in practice", respectively, when one is describing political or legal situations.
In a legal context, de jure is also translated as "concerning law". A practice may exist de facto, where, for example, the people obey a contract as though there were a law enforcing it, yet there is no such law. A process known as "desuatude" may allow de facto practices to replace obsolete de jure laws. On the other hand, practices may exist de jure and not be obeyed or observed by the people.