**CONDITION (IN LEGAL ACTS).** — The term *c.* (condition) is used to designate two distinct categories of legal concepts. By *c.* are meant both the presuppositions, logical antecedents, and elements of a legal act (*conditio iuris*), the necessary requirements for its validity (*conditio essentialis*) or for its lawfulness (*conditiones accidentales*), as well as the dispositions of will (*conditio voluntatis*), which add to a legal act (v.) a circumstance upon which its validity depends: “a circumstance added to the act from which its validity depends.”
Within this second concept falls, as a species within a genus, the *c.* in the strict sense, namely that disposition of will intended to make the efficacy or the termination of the act dependent upon the occurrence or non-occurrence of a future and uncertain event, also called a *c.* Once the *c.* is fulfilled or fails to be fulfilled, its effects (perfection or cessation of the act’s efficacy) normally retroact to the initial moment of the act.
To this category of proper *c.* there is opposed the category of improper *c.* (also understood as dispositions of will), by which the efficacy of the act is made dependent not upon a future and uncertain event, but upon a past or present circumstance (*conditio in praeteritum vel in praesens collatae*), so that the act is valid or invalid depending on whether what has been subjected to the *c.* exists or does not exist.
These are not properly *c.* but reservations, which share with *c.* their structure and legal consequences, inasmuch as in both figures a hypothesis is formulated that differs only in the quality of the apodosis (objective or real in improper *c.*, eventual or potential in proper ones), and inasmuch as the positive or negative resolution of the doubt regarding the existence of the element subjected to the *c.* operates as the occurrence or non-occurrence of the event.
Of improper *c.*, the *Codex Iuris Canonici* (CIC), besides in can. 1092 n. 4 (*c.* appended to matrimonial consent), treats in can. 104, where, regarding error that invalidates the act, alongside *error in substantia actus*, the error that renders the act dependent upon a *conditio sine qua non* is considered. However, in this second hypothesis, the figure of error (*falsum iudicium*) is not present, since error, as a theoretical act, can never be converted into a *c.*; rather, the figure of the reservation is present, which, as has been said, involves the formulation of a hypothesis that, if it does not correspond to reality, produces the nullity of the act to which it is subordinated.
Such a reservation must be explicit; otherwise, one cannot speak of a *c.*, but of one of those figures said to be akin to it, such as presupposition, or undeveloped *c.*, cause, or simple motive, and demonstration, or quality attributed to the desired object: concepts that are rather to be referred to the factual situation upon which the will operates, rather than to the will itself as it is concretized in the legal act.
Another figure akin to the *c.* is the *modus* (mode), for which V. MODO (MODE).
From what has been said, it is easy to perceive the difference that obtains between all the aforementioned figures (including the improper *c.*) and the proper or *de futuro* *c.*
The objective uncertainty of the future event further serves to distinguish the *c.* in question from a term (v.), and to exclude from the concept of proper *c.* necessary *c.* (*si crasi soli oriuntur*), naturally impossible *c.* (*si coelum digito tetigeris*), and purely potestative or arbitrary *c.* (*si volueris, si volueris*).
As a rule, necessary *c.*, if suspensive, and impossible *c.*, if resolutive, are considered as not having been appended; conversely, if the former are resolutive or the latter are suspensive, the act to which they are appended is devoid of any effect.
There are finally *c.* that are naturally possible but legally impossible (also called perplexing and absurd), which refer to circumstances incompatible with the nature and necessary effects of the legal act one seeks to bring into being. These may therefore be subsumed under the category of illicit or immoral *c.*, which either render the act invalid (*vitiant*) or are treated as not having been appended (*vitiantur*), depending on the natural or positive regulation of the act (generally, civil laws establish the nullity of the act if the illicit *c.* is appended to an inter vivos act, and instead the inefficacy of the *c.* in the case of mortis causa acts).
Having premised this, proper *c.* are distinguished: a) with regard to the production of the event, into potestative, causal, and mixed, depending on whether the event depends on the will (not mere arbitrariness) of one of the parties, on chance (or the will of a third party), or on the concurrence of both causes; b) with regard to their effects, into suspensive and resolutive, depending on whether the event (positive or negative) is assumed as the *c.* for the efficacy of the act or for its termination; c) with regard to their form, into positive (or affirmative) and negative.
In this regard, it must be clarified that the distinction of *c.* into positive and negative does not rest upon the grammatical form (positive or negative) adopted in their expression, but upon the manner in which the event in question must operate upon the pre-existing reality. If the nature of the event is such as to alter the present state of affairs (*si navis veniet ex Asia*), the *c.* is positive; in the opposite case (*si navis ex Asia non veniet*), it is negative.
As for the quality of *c.* with regard to their effects, it is not always easy to determine whether a *c.* appended to a legal act is suspensive or resolutive. This depends on the intention of the party who created the conditional legal act: if he intended to engage a legal situation but to promote its effects only upon the fulfillment of the *c.*, it is a suspensive *c.*; if, on the other hand, he intended to promote the effects of the act but to consider them as not produced should the *c.* fail to occur in the future, this will be considered a resolutive *c.*
*C.* may be appended to almost all legal acts of private law, and also to many of public law. In addition to the general principles set forth above, which apply especially to contracts and testamentary dispositions, positive law often provides special norms for *c.* in relation to certain categories of legal acts.
Thus, civil law, with regard to contracts (v. CONTRATTO), lays down norms for *c.* in rescripts (v. CLAUSOLA), in marriage (v.), in elections (v. PROVVISTA CANONICA), in the foundation of a benefice (v. BENEFICIO ECCLESIASTICO), in the renunciation of a benefice or a parish (v. RINUNCIA).