"Blackmun adopted the expansion to viability, and in a memo to the Justices of December 15 indicated that he would be revising the draft opinions to shift the decisive point from the end of the first trimester to viability. On December 21, Blackmun circulated his revised third draft in Roe, the first to include the trimester framework and the first to identify the right as extending to viability. At this point, the abortion cases were effectively decided."