IN LEGAL TERMS. — The term appears in Roman legal sources, not only to denote the final part, but also a heading or a body of provisions in the praetor’s edict on a specific subject (clausula edictalis).
Hence the dual meaning that the term has in ordinary legal language. In fact, *clausula* (c.) is understood both as a heading or article forming part of the content of a legal transaction (e.g., *clausula contractus*, *clausula testamentaria*), and, in a strict sense, as a provision expressed in a brief, meaningful formula sanctioned by usage, which is inserted into an act (normally as an appendix) to give it a particular effect, whether extensive or restrictive.
Thus, in Roman law, there is the *clausula codicillaris*, which ensures that a will, even if declared invalid as such, may at least take effect as a codicil; in modern contract law, there are the *clausula poenalis*, *clausula compromissoria*, *clausula rebus sic stantibus*, *clausula de concurrentia*, and so on; and outside private law, the *clausula provisionalis* (CIC, can. 1917 § 2), the *clausula nationis favorabilissimae*, etc.
To attempt a systematic classification of the most frequently used *clausulae* in canon law (of which old treatises provide endless lists), it may be said that, with respect to their source, they are distinguished into *clausulae communes*, those customarily appended to contracts, wills, judicial acts of the parties, etc.; and *clausulae apostolicae*, proper to acts of the Pope.
The notion of *clausula* in canon law is of particular interest in the doctrine of rescripts (v.), where, however, the term is used interchangeably with “condition” in a broad sense, to signify both the essential circumstances for the validity of the rescript (e.g., the *clausula* or condition *“si prece veritate nitantur”*, which is always to be understood), and the accidental and modal circumstances, such as commands, warnings (*clausulae mere praeceptivae*), instructions, commonly directed to the executor of the rescript (*clausulae instructivae*), whose non-observance, while undoubtedly constituting a wrong, is nevertheless devoid of the sanction of nullity of the rescript.
Yet this notion, developed in the context of rescripts and certainly not confined to it, does not exhaust, as has been seen and will be further seen, the entire concept of *clausula* in the strict sense.
In general terms, from the perspective of content, two categories of *clausulae* may be distinguished: those of purely positive content, which establish the conditions for the validity of the act, determine its efficacy (e.g., the *clausula rebus sic stantibus*) and its modalities; and those of negative content, consisting of provisions that extend or restrict the efficacy of the act itself, in derogation of the norms of common law (*clausulae derogatoriae*).
In this second category fall: a) *clausulae* by which a pre-existing legal state is modified, through the abrogation of norms or the revocation of concessions (*clausulae abrogatoriae*, *revocatoriae*): one may recall in this regard the usual formulas *“revocatis vel non obstantibus...”*; b) those by which it is intended to prevent the formation of a possible legal state (*clausulae prohibitoriae*), as, for example, in the formula *“exclusa in futuro qualibet consuetudine contraria”*; c) those that limit in time the normal efficacy of the act (*clausulae peremptoriae*); d) and finally those that protect the act from possible challenges, by providing for its prior confirmation (*clausulae praeiudiciales*).
As regards the interpretation of *clausulae* with a view to determining their effects, no general and certain rule can, as is obvious, be laid down. With regard to the first category (*clausulae*-conditions), the CIC provides, in can. 39, a formalistic criterion, which, although laid down for rescripts, may be extended also to other acts and, by analogy, to laws: conditions are presumed essential for the validity of the act when they are expressed with the particles *si*, *dummodo* or an equivalent.
As for the other category, the meaning and efficacy of some frequently used *clausulae* are sometimes determined by the CIC itself, sometimes by doctrine.
Thus, for example, by the peremptory *clausula* *“ad beneficium nostrum”* (v.) or another equivalent (e.g., *“donec voluero”*, but not *“donec revocavero”* or *“usque ad revocationem”* or *“ad beneficium Ordinarii pro tempore”*, *“ad beneficium Sedis”*), the efficacy of the rescript is limited in time, which normally continues even after the resolution of the granting authority (cf. can. 73, in relation to can. 61); by the *clausula* *“motu proprio”* (can. 43), the invalidity of the rescript arising from the concealment of facts deemed necessary is sanctioned (this being a derogation from the principle established in the preceding cann. 40 and 42), inasmuch as it is presumed that, by the adoption of the aforesaid *clausula*, the will of the rescript has become independent of the motives stated in the petition; by the *clausulae praeiudiciales maiores* (*clausula* *“ex certa scientia”*, *“subdata”*, *“decretum irritans”*, etc.), to use the characteristic expression of Cardinal De Luca, the judge and the parties are silenced and bound, that is to say, the cognizance of any challenge to the act is withdrawn from every other judge except the Roman Pontiff himself.