As you well know, IANAL, so I may be spewing misinformation on this one because I haven't researched it. But ... a judge must interpret the law. So her decision was an interpretation of applicable law. No, judges may not make up their own law. If she is guilty of doing so, her decision on the law will be reversed upon appeal. Accountabilty for errant judical rulings is addressed when a higher court reviews the lower court's ruling(s).
One of the attorneys on the Sanity Squad will correct my errors if necessary.
Title 28 of the U.S. Code - The Judiciary and Judicial Procedure
http://www.law.cornell.edu/uscode/28/usc_sup_01_28.html
On Judicial Misconduct and Discipline
http://www.tulanelink.com/tulanelink/sassower_01a.htm