Kennedy has often played the role of the reluctant but reliable vote for the bare pro-choice majority. He reportedly switched his vote in 1992 when he was ready to overrule Roe v. Wade in the Planned Parenthood v. Casey decision. He would instead join in the plurality decision upholding the essence of Roe while adopting a new “undue burden” test.

He has largely stayed faithful to that line in striking down laws that have “the purpose or effect of placing a substantial obstacle in the path of a woman seeking an abortion of a nonviable fetus.” While he upheld the ban on late term abortions in Gonzales v. Carhart in 2007, he voted to strike down Nebraska’s ban on partial-birth abortions in Stenberg v. Carhart in 2000. More recently, he voted to strike down the safety standards imposed on abortion clinics in last year’s Whole Women’s Health v. Hellerstedt.

Although his position on abortion has been described as everything from nuanced to incomprehensible, it has largely favored the original right under Roe. That is the very measure that conservatives have long used for whether a nominee is truly conservative and, without the filibuster rule, conservative voters will expect senators to deliver. Of course, that could leave Chief Justice John Roberts as a potential swing vote as he was over health care. However, the Kennedy salient would be gone.