This is driving me crazy. I have asked many people that refer to the U.S. government's free reign on the use of patents in general and RSA technology in particular. There are a lot of very respectable and reputable specialists on this list and I hope they can answer my quest ion. What *specifically* gives the government the *right* to use patents developed `with public money' without licensing, or the RSA patent in particular (if the two are not the same)? My understanding -- and I've never seen the original document, so I can be wrong -- is that the statutes providing for grants to professors have such provisions. That is, barring all patents developed under such grants could be seen as stifling private initiative. But permitting the inventor to retain all rights is unfair, since the government funded the work. Hence the compromise: patents are permitted in such cases, but the government gets free use. As for the ``personal use'' question -- I've never heard of such a thing. The law gives gives the patent holder the right to bar others from selling, making, or *using* the protected invention. There is a court ruling permitting use of patented materials for experimental purposes; some people may be extending that. One more word on patents. The claim that 50% of patents are thrown out when challenged may or may not be accurate; however, it is very time-dependent. Such things go in cycles, depending on the makeup of the Supreme Court. During, say, the 1970's, there was a substantial component on the court that opposed the concept of patents, so many more challenges were upheld. I need not point out that the makeup of the court has changed substantially in recent years; during the 1980's, many more patents were upheld. I've seen one or two articles indicating that the pendulum is starting to swing back, but it's harder to say now; most patent cases these days only go as high as the Court of Appeals for the Federal Circuit. --Steve Bellovin