Some federal courts enjoy jurisdiction, the right to hear a case for which they would not ordinarily have original jurisdiction.

The answer is supplemental jurisdiction.

Explanation:

Supplemental jurisdiction consists of United States federal courts' authority to hear other claims that have some relationship with the original claim. However, the court would not have the subject-matter jurisdiction to hear those other claims independently.

Thus, a federal court can hear a federal claim, and at the same time it can hear in a specific way state law claims that have a relationship with the federal claim.  

answer; because they must appeal to a broad cross-section of the population;