In general, here's how patent damages work (in the U.S.): 1. If the patent owner can establish that it would have made the sales that the infringer did, then t

In general, here's how patent damages work (in the U.S.): 1. If the patent owner can establish that it would have made the sales that the infringer did, then the patent owner is entitled to the profits it would have made from those sales. (That's often hard for a patent owner to prove, especially if it is a "non-practicing entity.") Not surprisingly, this is referred to as lost-profits damages. 2. Otherwise, the patent owner is entitled to a "reasonable" royalty on the sales the infringer made that are covered by one or more valid patent claims. The royalty is supposed to be determined by assessing -- in hindsight -- what a reasonable licensor and reasonable licensee would have agreed to before the infringement began. (There are variations on, and complications in, the analysis that I won't go into here.) 3. Usually what happens at trial is that each side puts an expert witness on the stand to walk the jury through his or her analysis of what a reasonable royalty would have been. Opposing experts' analyses can vary wildly. 4. All of these determinations are made by a preponderance of the evidence. That is, jurors are instructed by the judge that they are to determine whether the patent owner has submitted evidence sufficient to make the patent owner's damages claim "more likely than not." [EDIT: As a practical matter, jurors often can be influenced by which expert witness they found more believable and/or likable, and by their perception of who is the good guy and who the bad guy.] 5. See http://www.virginiaiplaw.com/2010/03/articles/patent-litigation/federal-circuit-requiring-more-rigorous-proof-of-patent-damages/ http://www.virginiaiplaw.com/2010/03/articles/patent-litigat... for a summary of some recent contentious issues in the patent-damages area. 6. If the jury finds that patent owner has proved, by clear and convincing evidence (not just a preponderance of the evidence), that the infringement was "willful," then the judge (not the jury) has the authority: a) to increase the damage award up to treble damages; and/or b) to find that the case was "exceptional" and award the patent owner its reasonable attorneys' fees and expenses of litigation. 7. As a practical matter, any prospective juror who knows anything about the subject matter is likely to be excluded. [EDIT: That's because patent-owner lawyers don't want jurors to have pre-conceived notions about what is or isn't patentable in that field.] FOOTNOTE: It's not well-known that lawyers don't pick a jury, they unpick it. Usually, prospective jurors are randomly assigned sequential numbers from 1 to N. Jurors can be excluded "for cause" (e.g., because they know one of the parties, etc.), or by the lawyers' using their limited number of peremptory strikes. The first 12 people remaining (or six people in some cases) become the jury. 8. EDIT: The discussion above presupposes (i) that the patent owner has proved that at least one claim in the patent has been infringed, and (ii) that the accused infringer has not proved, by clear and convincing evidence, that all infringed claims are invalid.