[Old Retired Army Guy]

A tie would have allowed the Law to stand as is which would have validated the mandate under the Commerce Clause in lieu of it being labled a Tax.

[Ingtar]

There were conflicting lower court rulings. Wouldn’t that have left the entire issue “undecided”?

[old republic]

The lower court decision would have stood in the event of a tie vote at the SCOTUS. However, if that had happened, then the case would NOT have counted as a Supreme Court precedent. Only a SCOTUS majority vote can produce an precedent which is binding on the lower courts, which we no have. Historically, these precedents tend to be very difficult to overturn.