Markush doctrine (mahr-k<<schwa>>sh).Patents. An exception to the policy against the use of alternative language in claims, by which in certain claims (esp. those involving chemical components) a claimant can use an alternative, subgeneric phrase when there is no applicable, commonly accepted generic expression. • Characterized by a phrase such as “selected from the group consisting of,” the claim includes a group of substances any one of which could serve the same function in the process. The term Markush comes from Dr. Eugene A. Markush, who was granted a dye-preparation patent in 1923. Ex parte Markush, 1925 Dec. Comm’r Pat. 126. See MARKUSH GROUP. [Cases: Patents 101(7).]

“The Patent Office early adopted a policy against use of alternative language in claims. Thus, a claimant could not use the specific alternative phrase ‘glass or plastic’ but could use a generic phrase (such as ‘impervious transparent material’) that would cover effectively the desired alternatives. The Markush doctrine developed as an exception …. With chemical compounds there may be no suitable phrase to cover the alternatives. Under limited circumstances a claimant could use an artificial or coined subgeneric group in the form of ‘material selected from the group consisting of X, Y, and Z.’ ” 2 Donald S. Chisum, Patents§ 8.06[2], at 8-119 to 8-120 (1992).

[Blacks Law 8th]