SAN FRANCISCO — Bikram yoga aficionados can stretch and sweat with impunity following a Ninth Circuit ruling that the practice's signature sequence of poses is not copyrightable.

The U.S. Court of Appeals for the Ninth Circuit on Thursday found that yogi Bikram Choudhury's series of 26 yoga poses and two breathing exercises is an “unprotectable idea,” and that Choudhury cannot restrict its use.

The panel's unanimous opinion reaffirms the “idea/expression dichotomy,” a fundamental principle of copyright law that says the expression of ideas is copyrightable, but the ideas themselves are not. For example, the panel pointed out, a surgeon who copyrights a book describing how to perform a complicated surgery does not then have the exclusive right to perform the surgery.