Why does a patent not give us the right to use our invention?

Since there's been a difference of opinion, I thought I would provide a third answer. Steven Weinrieb is absolutely correct that a patent does NOT provide any right to make, use or sell the patented invention. The reason is quite simple to understand through example. Suppose your invention has four parts A, B, C, D, and your patent covers the combination A+B+C+D, which you were able to patent because A+B+C+D is an incredibly useful and surprising combination. Theoretically, all of parts A, B, C, and D could be separately patented by others, in which case you would be infringing all of those prior patents if you make or sell your invention. In other words, it's absolutely possible and commonplace to obtain a patent on something that includes portions which were previously patented by others. This is what a freedom to operate analysis is all about.

Shawn Kolitch, Ph.D.
Shareholder, Kolisch Hartwell, P.C.
Portland, Oregon, USA
shawn@khpatent.com