How would one distinguish successful from unsuccessful assertions of judicial power? What is it that puts Marbury in one class and Dred Scott in another?

Answer 1

In the Marbury case, the Supreme Court threw out the suit because it was based on an unconstitutional statute.

Check these sites.

http://en.wikipedia.org/wiki/Marbury_v._Madison

http://en.wikipedia.org/wiki/Dred_Scott