LUCID INTERVALS. In Medical Jurispru dence. Periods in which an insane person is so far free from his disease that the ordinary legal consequences of insanity do not apply to acts done therein.
A lucid interval is not a perfect restora tion to reason, but a restoration so far as to be able, beyond doubt, to comprehend and do the act with such perception, memory, and judgment as to make it a legal act. Frazer v.'Frazer, 2 Del. Ch. 263; Whart. & Stine, Med. Jur. §. 2.
Lucid intervals were regarded as more common and characterized by greater men tal clearness and vigor, by earlier medical writers than the later ones. This view was shared by legal authorities, who treated a lucid interval as a complete, though tempo rary, restoration. D'Aguesseau, in the case of the Abbe d'Orldans, concludes: "It must not be a mere diminution,. a remission, of the complaint, but a kind of temporary cure, an intermission so clearly marked as in every respect to resemble the restoration of health." Pothier, Obl., Evans' ed. 579. And Lord Thurlow characterized it as "an interval in which the mind, having thrown off the dis ease, had recovered its general habit." 3 Bro. C. C. 234. Possibly there may be such intermissions of absolute restoration but they are of rare occurrence. Usually, with apparent clearness, there is a real loss of mental force and acuteness,—not necessarily apparent to a superficial observer, but, upon critical examination, showing confusion of ideas and singularity of behavior indicative of serious though latent disease. In this con dition the patient may hold some correct no tions; even on a matter of business, and yet be quite incompetent to embrace all the rela tions connected with a contract or a will, even though no delusion was present to warp his judgment. This conclusion is aided by the recorded experiences of patients after en tire recovery. See Georget, Des Mal. Men. 46; Reid, Essays on Hypochondriacal Af fections, Essay 21; Combe, Men. Derang. 241; Ray, Med. Jur. 376.
Of late years the interest of the courts in connection with lucid intervals both in civil and criminal cases is confined to the ascer tainment of the mental capacity of the per son concerned with relation to the transac tion in question. This idea has even been
carried to the excess of treating the reason ableness of the act itself as the test of the capacity of the individual, or the existence of a lucid interval ; 1 Phill. Lect. 90; 2 C. & P. 415. But this has been said to be a mere begging of the question, inasmuch as persons undeniably insane constantly do and say things which appear perfectly rational; 2 Hagg. 433, where two wills, both perfectly reasonable, were set aside because within a short time prior to their execution there had been admitted insanity. And it was said: "When there is not actual recovery, and a return to the management of himself and his concerns . . . the proof of a lucid inter val is extremely difficult." In criminal cases this difficulty is inten sified, since the very term lucid interval im plies that the disease has not disappeared, but only that its outward manifestations have ceased and there remains an abnormal condition of the brain, by whatever name it may be called, whereby the power of the mind to sustain provocations, resist tempta tions, or withstand any other causes of ex citement, is greatly weakened. Being in their nature, as temporary and of uncertain dura tion, there is no presumption that they will continue ; Pike v. Pike, 104 Ala. 642, 16 South. 689 ; contra, Wright v. Jackson, 59 Wis. 569, 18 N. W. 486; and see Snow v. Benton, 28 Ill. 306.
Lucid intervals are not to be confounded with periods of apparent recovery between two successive attacks of mental disorder, nor with transitions from one phase of in sanity to another. These are said to be equivocal conditions during which persons subjected to them labor under a degree of nervous irritability, which renders them pe culiarly susceptible to many of those inci dents and influences which lead to crime; Ray, Med. Jur. ch. Luc. Int.