Was Chief Justice Roger Taney correct in arguing that the Court had to decide both the right of blacks to sue and the constitutionality of the Missouri Compromise in Dred Scott v. Sandford?
I would argue that Chief Justice Taney was not correct to say that the Supreme Court of the United States had to decide both of these issues. The Court could have decided the Dred Scott case even if it only ruled on one of these two questions. Ruling on both questions was unnecessary, which is one reason why this case is often seen as a case in which the Court overreached itself.
In this case, the Court had to decide whether Dred Scott was a free man. In order to say that he was free, it would have had to rule in his favor on two issues. First, it would have had to say that he had the right to sue. Second, it would have to find that, if he had the right to sue, he would still lose his law suit because there was no legal reason he should be free. If the Court ruled against Scott on either of these issues, it would not have had to rule on the other issue.
The Court found first that Scott had no standing to sue. It said that only citizens of the United States could bring law suits in federal court. It said that Scott could not be a citizen of the United States because he was black. The Court argued that the Framers had not intended to include blacks among the citizens of the United States at the time that they wrote the Constitution.
Once the Court had made this decision, it no longer needed to decide this case on the merits. It could have simply dismissed the case because Scott had no standing. Instead, Taney decided to rule on the issue of the Missouri Compromise. He said that Scott would not be free even if he had standing to sue because the Missouri Compromise, which made the Wisconsin Territory free, was unconstitutional. This was unnecessary.
Scholars say that it is best for the Supreme Court to make its decisions as narrow as possible. The Court should not declare major laws passed by Congress to be unconstitutional unless it is absolutely necessary to do so. In this case, Taney could have simply stated that Scott had no standing and dismissed the case. Instead, he chose to interject the Court into the political issue of slavery. This was a grave mistake. Taney would not have had to decide on both of these issues. He could have and perhaps should have ruled only on the first issue you mention.