Gov. Mary Fallin (R-OK) has rarely met an abortion restriction she did not like. In 2008, as a member of Congress, she co-sponsored a bill to treat fetuses as people and give them equal protection under the U.S. Constitution. Since she became governor in 2011, she has signed legislation to ban many second trimester abortions, require longer waiting periods, and restrict access to medication abortion — laws that were later found to be unconstitutional.

So it came as something of a surprise when Fallin announced Friday that she had decided to veto a bill to make it a felony for doctors to perform abortions and to revoke their licenses if they carry out the procedure when it is not absolutely necessary to save the life of the woman. She described the bill as “unconstitutional” — a view shared by legal experts.

But rather than reject the legislation on the grounds that doctors should be free to do their jobs or that the U.S. Supreme Court’s 1991 Planned Parenthood v. Casey ruling explicitly rejects state abortion laws that impose an “undue burden” or “substantial obstacle in the path of a woman seeking an abortion before the fetus attains viability,” Fallin made clear that her issue with the measure, Senate Bill 1552, was entirely with its less-than-specific phrasing.

“Although Senate Bill 1552 excludes a mother’s threat of self-harm from the exception preserving the life of the mother, Senate Bill 1552 does not define ‘necessary to preserve the life of the mother,’” she wrote in her veto message. “The absence of any definition, analysis or medical standard renders this exception vague, indefinite and vulnerable to subjective interpretation and application.” Fallin added that state court precedent requires that laws be clear enough “that all persons of ordinary intelligence” can understand them.

In other words, Fallin objected only to the fact that there might be cases where it was not clear that the procedure was necessary to save a life.

Fallin added that while this law’s language was too “vague and ambiguous,” she supports a “re-examination of the United States Supreme Court’s decision in Roe v. Wade,” and “the appointment of a conservative, pro-life justice to the United States Supreme Court.”

Even so, the bill’s sponsor, Sen. Nathan Dahm (R) blasted the veto “from a person who claims to be pro-life,” and indicated that he hopes the Republican-controlled legislature will attempt to override the veto before the session ends on May 27.