DOLO. — The term d. is used in law in two different senses: as a defect of the will in juridical acts, or as the subjective element of unlawful acts, especially crimes (v.).
1. In the first sense, d. (more properly called dolus malus, as opposed to dolus bonus) consists in deceit, schemes, or artifices used to deceive someone in such a way as to induce him to perform a juridical act which, had he not been deceived, he would not have performed (dolus causam dans), or would have performed only on more advantageous terms (dolus incidens).
It constitutes, together with error and violence, one of the three fundamental defects of the will that may produce the nullity or voidability of a juridical act. In reality, it may also be regarded as a subspecies of error, distinguished by the circumstance that the error is caused by another’s deception; and indeed the principles and rules relating to d. are chiefly relevant in cases where the error resulting from it is not in itself sufficient to invalidate (that is, independently of the fact that it is the product of another’s d.) the juridical act.
An act performed as a result of another’s d. is generally not void, but merely voidable (v. NULLITÀ): that is, the person who was deceived, or his heirs (and, in the case of certain acts, any interested party), may, within a certain period (under Italian law, five years; canon law refers the matter to civil law) from the discovery of the d., request the judicial authority to annul the act. This applies, however, only where the d. is causam dans, that is, such that, had the d. not occurred, the act would not have been performed; if, on the other hand, it is incidens, the act is valid, without prejudice to the obligation of the author of the d. to compensate the damage (CIC, cann. 103 § 2 and 1684–85; Italian Civil Code, arts. 624, 1439–46). In cases where the author of an act could seek its annulment on the ground of d. (that is, has, as it is said, an action for d.), he may also plead d. (that is, has the defense of d.) if he is summoned before a court to perform the obligations arising from the act (as expressly provided by can. 1686).
It should also be noted that civil law generally, in bilateral juridical acts (v. ATTO GIURIDICO), attaches no significance to d. unless it is employed by one of the two contracting parties to the detriment of the other, or unless, although employed by an unrelated third party, it was known to the contracting party who benefits from it (cf. art. 1439 of the Italian Civil Code).
The law sometimes derogates from the principles set out above with regard to certain types of juridical acts. The derogation may take two different forms: either the acts vitiated by d. are considered void, rather than merely voidable (but this almost never occurs), or they are considered entirely valid (that is, not even voidable). A very important example of this second derogation is found in canon law and in almost all civil legislations with regard to marriage: in marriage, d., even when employed by one of the contracting parties to the detriment of the other, does not affect the validity of the act; only the error resulting from d. may constitute a ground for the nullity (under civil laws, also for the voidability) of the marriage, but only provided that it is such that, independently of the d., it would in itself have produced that invalidity (v. ERRORE).
2. In the matter of unlawful acts, one speaks of d., in contrast to fault (v.), when the author of an unlawful act has acted with the intention of producing the harm or danger in which the unlawfulness consists.
Outside the field of criminal law, unlawful acts are considered chiefly with regard to the obligation arising from them to compensate the damage. And since that obligation exists whether the unlawful act was committed with d. or merely with fault in the strict sense, the distinction between d. and fault is not of great importance: it may be said that it is relevant only in this respect, that when two persons conclude an agreement exempting one of them from the obligation to compensate damage caused by that person to the other, such agreement, if concluded before the unlawful act is committed, is void insofar as it concerns damage caused intentionally, that is, the so-called pactum de dolo non praestando is void (and in modern law, on the basis, moreover, of Roman law, gross negligence is equated with d.).
The distinction between d. and fault is instead of the greatest importance in criminal law, since many acts constitute crimes only if committed with d. (v. DELITTO). For the moral aspect V. FRODE.