I would like to ask about the status of a patent if an independent claim is found to have been anticipated by a previous patent but a claim that is dependent on it has not.
For example, what would be the position of a particular US patent if at some point following the issue of the patent, claim 1 is found to be invalid because of the late discovery of an earlier patent covering the subject matter of that claim, but claim 2 which is dependent on claim 1 does not appear to have been anticipated.
Clearly the patent can no longer rely on claim 1, but is it legally enforceable with respect to claim 2? That is, if someone infringes claim 2, can the inventor use claim 2 to protect his or her right to the subject matter in that claim?
Or does claim 2 become invalid on account of the fact that it is dependent on an invalid claim. In that circumstance can the inventor do anything to maintain patent cover with respect to claim 2?