Since I don't have a legal background, I had to Google "
stare decisis". From what I can tell, that is the legal principal which states that judges in a lower court are obliged to respect a binding precedent established by a superior court.
Seems to me like Walker, in his ruling to overturn Proposition 8, blatantly disregarded the U.S. Supreme Court's previous decision in Baker v. Nelson with respect to the 14th amendment and same-sex marriage.
That seems like a no-no.