The four-pronged test from the SCOTUS ruling in 1977 (Complete Auto Transit, Inc. v. Brady) is the standing standard for commerce clause nexus now that Quill is gone. Accordingly, South Dakota’s law, or any like it, will be enforceable on remand if it:
- applies to an activity with a substantial nexus with the taxing state – (Substantial Nexus no longer physical, economic will do)
- Fairly Apportioned,
- Does Not Discriminate Against Interstate Commerce, and
- is Fairly Related to the services the state provides.