All of the licenses described in this book can be broken up into two parts. The first part asserts that the person granting the license, the licensor, has the right to license the work to which the license applies. This representation may be implicit or explicit, and may be limited to specific types of rights. A licensor may, for example, assert that he has only applicable rights under copyright to the licensed work and makes no representation about patent rights that may apply to it. The second part of every license is a grant (again, however limited) by the licensor to the licensee of rights to that licensed work.

Obviously, both parts of the license need to be there in order for the license to be effective. When the first part of the license is there and the licensor has all of the rights necessary to grant them to the licensee, the only question is the relationship between the licensor and the licensee under the terms of the license. However, significant complications arise when a third party has legitimate legal claims to the work purporting to be licensed.

In the case of copyrights, a creator of an original work (defined in the legal, not the artistic sense), can confidently license that work, at least to the extent to which it may be governed by copyright law. The creator (hopefully) knows that he or she has not plagiarized the work from another and therefore has the right to license it.

Patents, however, present more complicated issues. It ...