In the 1975 case of Thermtron Products, Inc. v. Hermansdorfer, the U.S Supreme Court ruled that federal courts cannot remand a case to state court on grounds not specified in section 1447(c) of Title 28 of the United States Code. The dispute began when Thermtron Products filed a lawsuit against certain defendants in Kentucky state court for damages resulting from alleged defamation and interference with contractual relations. One defendant removed the suit to federal district court based on diversity jurisdiction but was later dismissed from the action leaving only non-diverse parties remaining. The District Judge then sent back (remanded) this case to state court citing docket congestion as his reason which is not one of those listed under section 1447(c). On appeal by Thermtron, it was held that such an order could be reviewed by higher courts despite language in Section 1447(d) seeming to bar review because it exceeded statutory authority granted under Section 1447(c). Therefore, remanding due to heavy workload or other reasons beyond what's mentioned within statute is improper.

In the dissenting opinion for Thermtron Products, Inc. v. Hermansdorfer, Justice Rehnquist disagreed with the majority's interpretation of 28 U.S.C §1447(c), arguing that it was too narrow and did not consider Congress' intent to limit federal court jurisdiction over state law claims. He contended that a district judge should have discretion in remanding cases to state courts if they believe it would best serve justice or judicial economy, even when there is no lack of subject matter jurisdiction as defined by statute. In his view, this discretionary power was essential for managing caseloads effectively and maintaining good relations between federal and state courts.