"Between late November and the end of the year, Blackmun observes how he's thinking about moving what he called previously the "critical" line from the end of the first trimester to viability. He admits that he chose the end of the first trimester largely for marketing reasons, writing: "I selected the earlier point because I felt that it would be more easily accepted (by us as well as others) . . ." [Memorandum to the Conference from Harry Blackmun, dated December 11, 1972]. He is hesitant, however, if moving the line would cost him votes on the merits. ["I would be willing to recast the opinions at the later date (viability instead of the end of the first trimester), but I do not wish to do so if it would alienate any Justice who has expressed to me, either by writing or orally, that he is in general agreement, on the merits, with the circulated memorandum." [Id.]"