This section is from the book "Popular Law Library Vol7 Equity Jurisprudence, Trusts, Equity Pleading", by Albert H. Putney. Also available from Amazon: Popular Law-Dictionary.
The general rule may be stated to be that the breach of an affirmative promise in a contract cannot be prevented by injunction (the proper remedy being specific performance), but that the breach of a negative promise may be. For example, injunctions have been issued against the violation of such agreements as not to disclose information,16 or not to manufacture and sell a certain article.17
A contract affirmative in form often involves a negative in substance, and in such cases an injunction may be granted, the test being in the quality of the acts required, and not in the form of the language used.18
13 Chicago City R. Co. vs. General
Elec. Co., 74 I11. App., 465. 14 Shoemaker vs. South Bend Spark
Arrester Co., 135 Ind., 471; 35
N. E., 28. 15 In re Debs, 158 U. S., 564; United States vs. Elliott, 64 Fed., 27;
Crawford vs. Tyrell, 128 N. Y., 341; 28 N. E., 514. 16 Exchange Tel. Co. vs. Central News, 2 Ch., 48; 66 L. J. Ch., 672. 17 Kinsman vs. Parkhurst, 18 How., 289.