Intellectual Property Code
Section 80. Damages, Requirement of Notice. - Damages cannot be recovered for acts of infringement committed before the infringer had known, or had reasonable grounds to know of the patent. It is presumed that the infringer had known of the patent if on the patented product, or on the container or package in which the article is supplied to the public, or on the advertising material relating to the patented product or process, are placed the words "Philippine Patent" with the number of the patent. (Sec. 44, R.A. No. 165a)