In article ,
Ben Bradley wrote:

Does Philips have any claim on the actual redbook format, as far as
patent protection or such?

No, they do not. What they do have, indefinitely, is trademark
protection of the "Compact Disc Digital Audio" logo (there are various
versions referring to specific types of discs).

Check this out:

http://en.wikipedia.org/wiki/Compact_disc

Would such protection have run out by now?

Trademark protection never "runs out" unless the responsible party
chooses to allow others to use it. Unfortunately, many people interpret
this as a mandate for litigation, which it isn't.

I wonder if Philips' or other recording industry attorneys are
reading this thread....

Some sources indicate that Philips will make recorders which explicitly
defeat copy protection schemes that are counter to their requirements...