A more thorough explanation:

EX FICTIONE JURIS

Ex fictione juris is a Latin term that means "by a fiction of law." It refers to a legal concept where a court assumes something to be true, even if it is not, in order to achieve a certain legal outcome.

One example of ex fictione juris is the legal fiction of "adverse possession." This is a legal concept where someone can gain ownership of a piece of property by occupying it for a certain period of time, even if they do not have legal title to it. The court assumes that the person has been using the property with the owner's permission, even if they have not, in order to transfer ownership to the occupier.

Another example is the legal fiction of "incorporation by reference." This is a concept where a document can be considered part of another document, even if it is not physically attached or included in the original document. The court assumes that the referenced document is part of the original document, in order to achieve a certain legal outcome.

Ex fictione juris is a legal concept that allows courts to make assumptions in order to achieve a certain legal outcome. These assumptions are based on legal fictions, which are not necessarily true in reality, but are assumed to be true for legal purposes. The examples of adverse possession and incorporation by reference illustrate how ex fictione juris works in practice, by showing how courts can use legal fictions to achieve certain legal outcomes.