>I don't have the numbers...but even if more "minorities" are sentenced to death more frequently, it does not follow that "capital punishment" has a severe bias towards minorities. To prove bias, you must demonstrate a trend where minorities receive the death pentalty whereas a non-minority receive a lesser punishment for the same crime under the same circumstances in the same state.

Agreed. Read this:

http://www.voxeu.org/index.php?q=node/6581

<snip>
In summary, testing for racial bias when crimes rates and other unobservable characteristics vary across races is extremely difficult. We have had to make several assumptions to develop a test, and such test is only valid under these hypotheses. Conditional on this cautionary remark, we do find evidence of racial bias against minorities killing white victims in southern states of the US.