Patent fallacies

[Hal <74076.1041@CompuServe.COM>]

Another patent misconception, from what I understand, is that an unenforced
patent becomes invalid.  It is said that PKP is "forced" to go after PGP
because if they don't their patent will lose its force.
 
Several days ago Tom Morrow on the Extropians list said that this doctrine
applies to trademarks but not to patents.  Patents have a fixed 17 year
lifetime and failure to enforce against one user does not preclude the
patent owner from enforcing against another.  The folklore about the loss of
intellectual property rights that we are all familiar with (aspirin, zippers,
etc.) are all cases of trademark losses.
 
Tom is a law student, not a lawyer; also, I am a few days behind on my
Extropians reading so I don't know whether any follow-ups or corrections
were posted since his message.  But this principle seems to be in accordance
with what was posted here about selective enforcement of patents.
 
If this is in fact how patents behave, it is one less justification for
PKP's heavy-handed enforcement efforts against PGP.  It means that PKP could
choose not to enforce against PGP (or any other freeware program) without
losing any rights to enforce against others.  It would be interesting to
hear an authoritative opinion on this from a lawyer.
 
Hal