Who decides what the claims mean?
The judge decides claim construction under Markman v. Westview Instruments. Under Phillips v. AWH, claim words are read as a person skilled in the field would understand them in the context of the patent. The claims, specification, and prosecution history are central; dictionaries and expert evidence do not replace that context.
Why work on this early?
Identify which disputed words affect the product comparison or a prior-art argument, and explain why each proposed meaning matters. The schedule comes from the particular court and case. For example, Northern District of California Patent Local Rules 4-1 through 4-6 organize exchanges, briefing, discovery, and a hearing; they are not a nationwide timetable.
Does the PTAB use a different standard?
For inter partes review, 37 C.F.R. 42.100(b) specifies the same claim-construction standard used in a civil action under 35 U.S.C. 282(b). It also addresses consideration of prior court or ITC constructions timely made of record. Do not assume that an IPR uses the former broadest-reasonable-interpretation standard.