Tell me again: what is the job of a Supreme Court Justice?

This post isn't about war, but it is about rhetoric. Headline from today's Dallas Morning News: "Business leaders say Miers would add new perspective" (15A).

Quote from Sidney Stahl, a "lawyer friend of hers and a former council member . . . 'She had a good understanding of the business community in terms of the kinds of things that cities should do to attract business and industry.'"

Steve Taylor, president of a local Chamber of Commerce, "called her 'smart as hell'" and Donna Halstead, president of "an organization made up of leaders from Dallas' largest businesses" insisted that "'She would give other justices with no real world experience an opportunity to view issues from the private sector position.'"

I am not weighing in on Miers. But if conservatives take as a tenet that there should be no "legislating from the bench," then why is her "good understanding . . . of the kinds of things that cities should do to attract business" being raised? Are Supreme Court justices supposed to interpret the Constitution, or are they supposed to bring pro-business, pro-environment, pro-evolution, distinctly pro-anything perspectives to the Court?