Opposite tacks at the weather mark

Facts found

Both boats are close-hauled on the beat, approaching the windward mark to be left to port, both inside the zone. P is on port tack on the layline and hails for mark-room. S, on starboard, holds her course. P bears away hard to duck S and protests, claiming she was inside and entitled to mark-room.

You are on the protest committee.

How would you decide this?

Decide it cell by cell instead