OPERATION OF LAW. This term is applied to those rights which are cast upon a party by the law, without any act of his own; as, the right to an estate of one who dies intestate, is cast upon the heir at law, by operation of law; when a lessee for life enfeoffs him in reversion, or when the lessee and lessor join in a feoffment, or when a lessee for life or years accepts a new lease or demise from the lessor, there is a surrender of the first lease by operation of law. 9 B. & C. 298; 5 B. & C. 269; 2 B. & A. 119; 5 Taunt. 518.

OPERATIVE. A workman; one employed to perform labor for another.

2. This word is used in the bankrupt law of 19th August, 1841, s. 5, which directs that any person who shall have performed any labor as an operative in the service of anly bankrupt shall be entitled to receive the full amount of wages due to him for such labor, not exceeding twenty-fivedo llars; provided that such labor shall have been performed within six months next before the bankruptcy of his employer.

3. Under this act it has been decided that an apprentice who had done work beyond a task allotted to him by his master, commonly called overwork, under an agreement on the part of the master to pay for such work, was entitled as an operative. 1 Penn. Law Journ. 368. See 3 Rob. Adm. R. 237; 2 Cranch, 240 270.

OPINION, practice. A declaration by a counsel to his client of what the law is, according to his judgment, on a statement of facts submitted to him. The paper upon which an opinion is written is, by a figure of speech, also called an opinion.

2. The counsel should as far as practicable give, 1. A direct and positive opinion, meeting the point and effect of the question and separately, if the- questions proposed were properly divisible into several. 2. The reasons, succinctly stated, in support of such opinion. 3. A reference to the statute, rule or decision on the subject. 4. When the facts are susceptible of a small difference in the statement, a suggestion of the probability of such variation. 5. When some, important fact is stated as resting principally on the statement of the party interested, a suggestion ought to be made to inquire how that fact is to be proved. 6. A suggestion of the proper process or pleadings to be adopted. 7. A suggestion of what precautionary measures ought to be adopted. As to the value of an opinion, see 4 Penn, St. R. 28.

OPINION, evidence. An inference made, or conclusion drawn, by a witness from facts known to him,

2. In general a witness cannot be asked his opinion upon a particular question, for he is called to speak of facts only. But to this general rule there are exceptions; where matters of skill and judgment are involved, a person competent, particularly to understand such matters, may be asked his opinion, and it will be evidence. 4 Hill , 129; 1 Denio, 281; 2 Scam. 297; 2 N. H. Rep. 480; 2 Story, R. 421; see 8 W. & S. 61; 1 McMullan, 561 For example, an engi-neer may be called to say what, in his opinion, is the cause that a harbor has teen blocked up. 3 Dougl. R. 158; S. C. 26 Eng. C. L. Rep. 63; 1 Phil. Ev. 276; 4 T. R. 498. A ship builder may be asked his opinion on a question of sea-worthiness. Peake, N. P. C. 25; 10 Bingh. R. 57; 25 Eng. Com. Law Rep. 28.

3. Medical men are usually examined as to their judgment with regard to the cause of a person's death, who has suffered by violence. Vide Death. Of the sanity, 1 Addams, 244, or impotency, 3 Philm. 14, of an individual. Professional men are, however, confined to state facts and opinions within the scope of their professions, and are not allowed to give opinions on things of which the jury can as well judge. 5 Rogers' Rec. 26; 4 Wend. 320; 3 Fairf. 398; 3 Dana, 882; 1 Pennsyl. 161; 2 Halst. 244; 7 Verm. 161; 6 Rand. 704; 4 Yeates, 262; 9 Conn. 102; 3 N. H. Rep. 349; 5 H. & J. 488.

4. The unwritten or common law of foreign countries may be proved by the opinion of witnesses possessing professional skill. Story's Confl. of Laws, 530; 1 Cranch, 12, 38; 2 Cranch, 236; 6 Pet Rep. 763; Pet. C. C. R. 225; 2 Wash. C. C. R. 175; Id. 1; 5 Wend. Rep. 375; 2 Id. 411; 3 Pick. Rep. 293; 4 Conn. R. 517; 6 Conn: R. 486; 4 Bibb R. 73; 2 Marsh. Rep. 609; 5 Harr. & John. 86; 1 Johns. Rep. 385; 3 Johns. Rep. 105; 14 Mass., R. 455; 6 Conn. R. 508; 1 Verm. R. 336; 15 Serg. & Rawle, 87; 1, Louis. R. 153; 3 Id. 53; Cranch, 274. Vide also 14 Serg. & Rawle, 137; 3 N. Hamp. R. 349; 3 Yeates, 527; 1 Wheel. C. C. Rep. 205; 6 Rand. R. 704; 2 Russ. on Cr. 623; 4 Camp. R. 155; Russ. & Ry. 456; 2 Esp. C. 58; Foreign Laws; 3 Phillim. R. 449; 1 Eccl. R. 291.