Since a similar New York law was upheld by New York's highest court in March, the issue seems ripe for examination by the U.S. Supreme Court. Contributing to retailers' confusion is the Marketplace Fairness Act, which Congress passed in May.
That legislation requires internet sellers with at least $1 million in sales outside of their home states to collect state sales tax provided the state meets certain requirements. It was backed by Amazon.com, which now collects sales tax from residents of 13 states, including New York and California.