Etepha A.G. v. Director
[GR L-20635, Mar. 31, 1966]

“The validity of a cause for infringement is predicated upon colorable imitation. The phrase "colorable imitation" denotes such a "close or ingenious imitation as to be calculated to deceive ordinary persons, or such a resemblance to the original as to deceive an ordinary purchaser giving such attention as a purchaser usually gives, and to cause him to purchase the one supposing it to be the other." (87 C.J.S., p. 287.)”

“In the solution of a trademark infringement problem, regard too should be given to the class of persons who buy the particular product and the circumstances ordinarily attendant to its acquisition. (87 C.J.S., p. 295). The medicinal preparations, clothed with the trade marks in question, are unlike articles of everyday use such as candies, ice cream, milk, soft drinks and the like which may be freely obtained by anyone, anytime, anywhere. Petitioner's and respondent's products are to be dispensed upon medical prescription. An intending buyer must have to go first to a licensed doctor of medicine; he receives instructions as to what to purchase; he examines the product sold to him; he checks to find out whether it conforms to the medical prescription. Similarly, the pharmacist or druggist verifies the medicine sold. The margin of error in the acquisition of one for the other is quite remote. It is possible that buyers might be able to obtain Pertussin or Atussin without prescription. When this happens, then the buyer must be one thoroughly familiar with what he intends to get, else he would not have the temerity to ask for a medicine — specifically needed to cure a given ailment. For a person who purchases with open eyes is hardly the man to be deceived.”