The Illinois Supreme Court ruled Friday that the “Amazon tax” violated federal laws against “discriminatory taxes” on online sales, The Associated Press reports.

According to the Chicago Tribune, the high court’s ruling upholds a Cook County judge’s decision.

“Because we agree with the circuit court’s conclusion that the relevant portions of Public Act 96-1544 are preempted by federal law, we affirm the judgment of the circuit court,” the Illinois high court said in a ruling obtained by Bloomberg Businessweek.

The Chicago Tribune notes that consumers who reside in sales-tax states must pay a state sales tax on their online purchase. However, few consumers pay this tax on their state income tax returns. Thus, online transactions often cost less than in-store transactions if the retailer doesn’t collect a state sales tax at checkout.

According to Chicago Magazine, Illinois Governor Pat Quinn signed the Main Street Fairness Act in 2011. The act required online retailers, like Amazon, to pay state sales taxes in Illinois where they have affiliate sellers. The new law required the company to gather sales tax from sales made through links from sites headquartered in the Prairie State even if the retailer was not, CNET says.

To avoid having to collect state sales tax during online checkout, Amazon began cutting its ties to Illinois affiliates. The Chicago Tribune adds that some Illinois-based online companies, like CouponCabin.com, moved to neighboring states to avoid missing out on commissions from Amazon.com and other large online retailers.

According to The AP, the Illinois’ Department of Revenue may ask the U.S. Supreme Court to review the ruling.

What do you think of the Illinois high court’s decision? Will the U.S. Supreme Court review this ruling? Does having affiliate retailers in a state give a company a physical presence there? Start a conversation by sounding off in the comments section.