Some of these Latin phrases are used to describe some of the most basic aspects of criminal law or civil procedure, and so they will likely survive for the foreseeable future. However, some jurisdictions are making a conscious effort to eliminate the use of Latin terms in their statutes, which will gradually reduce the amount of Latinisms.
For example, in Canada, standard drafting practice at both the federal and provincial levels is to use English (and French) terms in preference to Latin. About twenty years ago, as part of a major statute revision, the federal government removed almost all Latin terms from the federal statutes. As well, law schools and bar courses emphasise the use of clear language and avoiding unnecessary Latinisms.
Also, as the law changes and develops, the legal concepts referred to by a Latin name may be eliminated and replaced with a new legal process, with a modern English (or French) name, instead of Latin. For example, in Canada at the federal level and in some provinces, the old common law prerogative writs to control administrative actions (e.g. - certiorari, mandamus) have been replaced with a single statutory remedy, called administrative judicial review. There are still references back to the common law origins of the concepts embodied in administrative judicial review, but the writs themselves and their Latin names have been abolished.
Of the two lists given by Derleth and friedo, I would say that the following are unlikely to disappear anytime soon, in Canada at least:
[ul]
[li] ex parte[/li][li] habeus [sic] corpus[/li][li] mens rea[/li]actus reus
[li] de facto[/li][li] de jure[/li][li] obiter dictum[/li][li] amicus curae[/li][li] ad hoc[/li][li] in absentia[/li][li] duces tecum[/li][/ul]
The following terms have been eliminated, in whole or in part, through changes to the law or revisions of the language used in statutes:
[ul][li] nolle prosequi[/li][li] pro se[/li][li] in limine[/li][li] ad litem[/li][li] bona fide[/li][li] ex post facto[/li][li] flagrante delicto[/li][li] in loco parentis[/ul][/li]
Mandamus and certiorari survive, but in varying degrees depending on the whether there has been statutory reforms to the language.