Rule 12 covers overlapping boats and says the windward boat must "keep clear". The definition of "keep clear" specifically permits the leeward boat to change course as it sees fit without making immediate contact - thus planting the onus squarely on the windward boat to maintain enough "room" that it can do such.
Would this include the case where the starboard-tack boat, clear-ahead, tacks to clear "A mark", but goes into irons....coming out of irons on the same starboard-tack (now sailing away and past "A mark") then sailing into and hitting the boat (previously clear astern) who was giving room (sailing past and to windward) and tacked while the the other boat was in irons?