Be sure to read the claims of the patent, carefully. You can think of the words and phrases in a given claim as the elements of an AND statement (or the inpu

Be sure to read the claims of the patent, carefully. You can think of the words and phrases in a given claim as the elements of an AND statement (or the input leads to an AND gate): If the claim returns TRUE when what you do is used as inputs, then that claim is infringed. The different claims in a patent are like the input leads to an OR gate: It only takes one infringed claim to make you liable. A claim can be infringed, even if Claim Element X is missing, if X is deemed present by an "equivalent." The analysis there can be complicated, so I won't go into it. Concerning patent validity, a patent is presumed valid; the burden is on the challenger to prove invalidity. This has to be done claim by claim. The courts have held -- wrongly, in my view, but there you go -- that proof of invalidity requires clear and convincing evidence, not just a preponderance of the evidence. Concerning open-sourcing, kits, etc.: Someone who intentionally induces infringement by another can be liable for the other person's infringement. There's also the concept of contributory infringement, which I won't go into here. There's no fair-use doctrine in patent law the way there is in copyright law. (Some people have argued for a fair-use exception for experimental scientific research; I don't recall offhand whether this is an established doctrine, but I don't think it is.) Usual disclaimer: Don't rely on this as a substitute for legal advice, YMMV, etc., etc. Good luck.