From Sci-Fi:

A federal judge in Los Angeles has found that Smallville may be infringing on the copyrights held by the widow and daughter of Jerome Siegel, who created the Superboy character for DC Comics, Variety reported. The March 23 summary judgment also found that Joanne Siegel and Laura Siegel Larson had successfully recaptured the Superboy rights as of Nov. 17, 2004.

If there is trouble for Smallville, there could be potential problems for the Legion of Superheroes show being developed.