Legalese

It refers to the language used in legal writing which is hard for laymen to read.

There is a plain lanugage movement for converting legal documents into simple language for laymen to understand it.

The reasons for using complex languages include the need for precision, avoidance of ambiguity and the need to cover broad areas while remaining brief.

Legal writing often contains words from Old English, Latin and French. This depends on the jurisdictions.
France and Britain have passed laws demanding legal language to be French and English respectively.