But it's not perfectly legal if the patent is valid. The infringement would just be against the original company if said company hadn't been bought.
Or are you suggesting that when a company is acquired all it's patents should become null and void?
And I wasn't suggesting that a companies patents should become null and void after purchase, however my logic was still horribly flawed here. I really should avoid the internets when tired.
Although I do think, as I have stated elsewhere, that a right to a monopoly should not be treated the same as any other property asset and should maybe have some limits in transferability and stuff like that.