Fumus boni iuris is a Latin phrase, used in European courts, meaning "presumption of sufficient legal basis" (literally meaning "smoke of a good right"), being a requirement for admission to certain benefits (for example, legal aid) or pronunciation of certain court actions (for example, so-called protective measures, injunctions).
It has a prima facie case when there is a possibility that the right claimed exists in practice: the existence of this assumption should be examined by the court which will decide according to the results of the fait accompli.

Example and Application

For example, when legal aid is sought, courts must examine whether the applicant has "proper right" thereto; if the claim the applicant founds their petition on in court is not unreasonable or reckless. When seizure is requested, the court must consider whether there are any facts that suggest the existence of a right to credit.
It is one of the two necessary conditions for civilians in actions (ex ART.700 CPC), but also in administrative appeals, when an injunction is imposed and is a measure that must exist prior to deliveration of the petition to suspend the act in question. The second prerequisite is "periculum in mora

Periculum in mora

Periculum in mora, Latin for "danger in delay", is one of two conditions which must be asserted in actions aimed at obtaining a protective order or injunction , to be granted the relief sought . The second condition is the c.d. Prima facie case...

", meaning "danger in delay", or that there is a danger that the time lag between action and discussion on the merits of the same facts may cause irreparable damage to the plaintiff, such as, for example, in the case of an injunction to suspend the felling of trees or a building.

See also:

1. List of legal Latin terms