De jure is an expression that means "concerning law

Law

Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

", as contrasted with de facto

De facto

De facto is a Latin expression that means "concerning fact." In law, it often means "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established." It is commonly used in contrast to de jure when referring to matters of law, governance, or...

, which means "concerning fact".

De jure = 'Legally', De facto = 'In fact'.

The terms de jure and de facto are used instead of "in law" and "in practice", respectively, when one is describing political

Politics

Politics is a process by which groups of people make collective decisions. The term is generally applied to the art or science of running governmental or state affairs, including behavior within civil governments, but also applies to institutions, fields, and special interest groups such as the...

 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 "desuetude

Desuetude

In law, desuetude is a doctrine that causes statutes, similar legislation or legal principles to lapse and become unenforceable by a long habit of non-enforcement or lapse of time. It is what happens to laws that are not repealed when they become obsolete...

" 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.

Examples

It is, in fact, possible to have multiple simultaneous de jure legalities that are not de facto. Between 1805 and 1918, the ruling dynasty of Egypt ruled de jure viceroys

Viceroy

A viceroy is a royal official who runs a country, colony, or province in the name of and as representative of the monarch. The term derives from the Latin prefix vice-, meaning "in the place of" and the French word roi, meaning king. A viceroy's province or larger territory is called a viceroyalty...

 of the Ottoman Empire

Ottoman Empire

The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

, but acted de facto independent rulers who maintained a polite fiction of Ottoman suzerainty

Suzerainty

Suzerainty occurs where a region or people is a tributary to a more powerful entity which controls its foreign affairs while allowing the tributary vassal state some limited domestic autonomy. The dominant entity in the suzerainty relationship, or the more powerful entity itself, is called a...

. However, from about 1875, the rulers had only de jure rule over Egypt

Egypt

Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

, as it had by then become a British puppet state. Thus, Egypt was by Ottoman law de jure a province of that empire, by Egyptian law de jure independent, but de facto was part of the British Empire

British Empire

The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

.