Why did Sandra Day O’Connor not join the decision to overrule Bowers v. Hardwick?

In the 2003 case Lawrence v. Texas, Justice Sandra Day O’Connor concurred with the majority's decision to strike down the Texas law criminalizing same-sex sexual conduct, but she did not join the portion of the opinion that overruled Bowers v. Hardwick.1

O’Connor’s disagreement stemmed from a difference in legal reasoning. While the majority relied on the due process clause of the Fourteenth Amendment to establish a right to privacy regarding intimate sexual conduct, O’Connor believed the case should have been decided based on the equal protection clause. She argued that the Texas law was unconstitutional because it discriminated against gay people by criminalizing their behavior while permitting identical conduct by heterosexual couples. Consequently, she defended the right of a state to outlaw certain intimate acts, provided that such bans were applied in a nondiscriminatory manner, rather than establishing a broad constitutional right to privacy that would necessitate overturning Bowers.1