The Federal Circuit recently injected some clarity into a key principle of patent damages known as the entire market value rule (EMVR). The EMVR allows a winning patentee to collect damages based on sales of unpatented technology if it is sold with patented technology, such as a patented muffler in an otherwise un-patented car. Applying EMVR, the market value of the entire car would be used as a starting point to calculate the appropriate value of the patented muffler. The EMVR can also be used to establish the value of a patented product, like a razor, if it leads to sales of additional, unpatented follow-on products, like razorblades.