Limitations on Damages

A. The Six Year Limitation
The patent statute imposes only two limitations on the patentee's entitlement to damages. First, the statute provides that "no recovery shall be had for any infringement committed more than six years prior to the filing of the complaint or counterclaim for infringement in the action."59 Although this section operates like a statute of limitations, it is not a true statute of limitations because it does not limit the right to bring suit in the first instance. It simply limits the period during which damages may be recovered.60

B. The Notice Limitation
The second limitation on damages relates to notice. Section 287 of the patent statute provides that a patentee, or its licensee, "may give notice to the public that the ... [patented article is] patented, either by fixing thereon the word 'patent' or the abbreviation 'pat.', together with the number of the patent."61 In the event of a failure to mark, damages may not be recovered "except on proof that the infringer was notified of the infringement and continued to infringe thereafter."62 The statute also provides that "[f]iling of an action for infringement shall constitute such notice."63 Hence, "[a patentee] is entitled to damages from the time when it either began marking its product in compliance with this [marking statute] ... or when it actually notified the accused infringer of its infringement"64 by filing suit or otherwise. This statutory section serves three purposes: (1) it helps to avoid innocent infringement; (2) it encourages patentees to give notice to the public that an article is patented; and (3) it aids the public in identifying patented articles.65

1. Actual notice
Actual notice is provided when the accused infringer "is notified, with specificity, that the patent holder believes that the recipient of the notice may be an infringer."66 Actual notice is given when the recipient is: (1) informed of the existence of the patent; (2) informed of the activity that is believed to be infringing; and (3) the notice is accompanied by a request to abate the infringing activity.67 Hence, actual notice usually comes in the form of a cease and desist letter.68

2. Constructive notice
To provide constructive notice, the patentee must show that it, or its licensee, "consistently marked substantially all" of its patented products pursuant to § 287.69 The question is whether the patentee's actions were sufficient to provide notice to the public, not whether the infringer actually knew about the patentee's patent.70

Process and method patents do not fall under the marking statute because "there is nothing to mark."71 However, if a patent contains both a product and a method claim, and if the product is actually sold, though not marked, the patentee is precluded from recovering damages for infringement of either the product or the method claims until actual notice is given.