The Supreme Court of the United States declined to get involved in state efforts to make online retailers collect sales taxes from customers. By policy the Supreme Court did not give reason for declining the case.
In many states if a company does not have a physical business presence they are not required to collect sales tax, which give web-based retailers an unfair advantage. The state would like to restore the competitive balance between online retailers and traditional brick-and-motar stores.
The National Conference of State Legislatures estimated that in 2012 the states lost $23 billion in uncollected taxes and about half were from online sales. For more information, read the full article here.