The Illinois Supreme Court, affirming a lower court decision, invalidated the state's "click-through" nexus law.  This law required out-of-state Internet retailers who use in-state web marketing "affiliates" to collect sales tax on all of the retailer's sales in Illinois. The Court found that the Illinois law was preempted by the federal Internet Tax Freedom Act ("ITFA"), which prohibits "discriminatory taxes on electronic commerce."
As a consequence of these cases, there is now a split between the New York and Illinois high courts on a substantially similar law, but for different reasons. While there is certainty regarding click-through nexus in Illinois (for at least the next year), these two decisions create more uncertainty nationwide and leaves unanswered what to do a year from now (assuming the ITFA is not extended).
A permanent resolution of this issue is only likely to occur if either: (1) the U.S. Supreme Court takes and decides these cases, or (2) Congress passes unifying legislation such as the currently pending Marketplace Fairness Act.
For more information on this decision and its implications click here.
 Performance Marketing Association, Inc. v. Hamer, Sup. Ct. of Ill., Docket No. 114496, 2013 IL 114496 (Oct. 18, 2013).