From Becoming Justice Blackmun:
Planned Parenthood v. Casey was argued on April 22, 1992. As in the Webster case three years earlier, it was not clear from the discussion at the conference whether Roe v. Wade itself was really on the table. But while there was uncertainty as to the details, Blackmun knew he would be writing a dissent.
Rehnquist circulated a twenty-seven-page draft majority opinion on May 27. "Wow! Pretty extreme!" Blackmun wrote in the margin of the first page. All the Pennsylvania law's provisions were upheld. Further, Rehnquist said the Court had been "mistaken in Roe when it classified a woman's decision to terminate her pregnancy as a 'fundamental right.' "
Then, suddenly, everything changed. Two days later, a handwritten note arrived from Anthony Kennedy. "Dear Harry, I need to see you as soon as you have a few free moments. I want to tell you about some developments in Planned Parenthood v. Casey, and at least part of what I say should come as welcome news."
When the two met the following day, Kennedy revealed that he, O'Connor, and Souter had been meeting privately and were jointly drafting an opinion that, far from overruling Roe, would save it-not in its details, but in its essence. The constitutional right to abortion would be preserved.