What does a reasonable royalty measure?
A royalty must reflect the patented invention's contribution. Ericsson v. D-Link explains why damages must separate patented value from unrelated features. A license on a different technology or business arrangement cannot supply a number without addressing the relevant differences. The task is to value the patented contribution, not assign value to unpatented features.
How are lost profits proved?
Mentor Graphics v. EVE-USA explains the need to prove what the owner would have earned but for infringement. One recognized, nonexclusive route examines demand, acceptable noninfringing alternatives, capacity to meet the demand, and the amount of lost profit. Lost profits and a royalty cannot compensate twice for the same loss.
Why does the damages period matter?
Where 35 U.S.C. 287(a) applies to patented articles, a failure to mark can prevent recovery for infringement before actual notice. Identify the relevant products, licensees, markings, notice, and dates before multiplying a sales figure by a proposed rate. The facts and applicable limits must support both the rate and the sales included.