Re: Multiple points
"The clean room discussion applies to patent, not copyright cases."
Clean room actually applies more to copyright than to patent since patent can protect the end in broad, regardless of the means (no matter how else it's made, no one else can legally make a new patented widget except you and your designees). Copyright only protect a specific means to an end. That's why Compaq was able to defeat IBM when it developed its clone BIOS (which was a case of copyright infringement; if it had been patent infringement, Compaq would not have been safe); Compaq clean-roomed the IBM BIOS.