Whether section 34 of the Judiciary Act of 1789 required the federal court to follow New York judicial decisions concerning the commercial-law effect of taking negotiable paper for a preexisting debt.
Holding
No. Section 34 required federal courts to follow state statutes and fixed local usages, but not state-court decisions on general commercial law.
Reasoning
The Court read the word “laws” in section 34 in its ordinary sense: state legislative enactments and established local customs with the force of law. Judicial decisions are evidence of the law, not themselves the law, because courts may reconsider, narrow, or overrule their own prior decisions.
State decisions remain controlling when they construe local statutes or govern rights tied to a particular locality, such as titles to real property. But the interpretation of ordinary commercial instruments presents a different kind of question. In those cases, federal and state courts alike seek the proper rule through general legal reasoning and commercial principles.
Negotiable-instrument law was, in the Court's view, part of a general commercial law shared across jurisdictions rather than a uniquely New York rule. New York decisions therefore deserved careful respect but did not conclusively bind the federal court. This conclusion allowed the Court to adopt its own understanding of the general law governing the bill.