Reverse engineering Implied License

Reverse engineering, meaning examining an article or apparatus to determine how it is made and how it works, is never illegal in the U.S., regardless of whether or not there are patents on the object.  What you do with the knowledge obtained by reverse engineering, however, can potentially give rise to infringement issues. Suppose, for example, the product has a patented aspect A, and based on your knowledge obtained by reverse engineering the product, you conceive of an additional aspect B which when combined with A improves the product.  A product practicing a combination of A and B could infringe the patent on aspect A, even though it is an improvement on a product that practices A alone. Consult a patent attorney for advice and counsel regarding potential infringement issues when improving a patented product.