What decides if a ruling is the law of the land?

The Supremacy Clause of the Constitution of the United States (Article VI, Clause 2), establishes that the Constitution, federal laws made pursuant to it, and treaties made under its authority, constitute the "supreme Law of the Land", and thus take priority over any conflicting state laws

Explanation:

the first part of the statute of limitations is the standard deadline, which gives victims of medical malpractice a certain number of years -- usually anywhere from two to six years, depending on the state -- after the malpractice occurred within which to file a lawsuit.