The Nebraska Supreme Court approved further procedures against Microsoft in a consumer class-action case that had previously been blocked by state courts.
The court reversed earlier rulings and sent the class-action lawsuit back to a lower court for further hearings.
The lawsuit alleged that Microsoft used its monopoly power to overcharge for Windows.
Its issue was whether indirect purchasers of a product can sue a manufacturer on antitrust grounds. There are precedents in US law which allow only direct purchasers of products to sue.
But the court noted that state law on the issue varies from federal law and in the case of Windows, end users affected by alleged monopoly abuse of pricing are typically indirect purchasers, or people who buy from retailers.
"To deny the indirect purchaser, who in this case is the ultimate purchaser, the right to seek relief from unlawful conduct would, essentially, remove the word consumer from the Consumer Protection Act," the court said.
On the federal level, similar lawsuits against Microsoft were dismissed last year because of this issue.
"Microsoft has been a market leader in delivering great software at very competitive prices, and has even reduced prices while adding features and functionality to its products," said a Microsoft spokeswoman.
In Minnesota, a class-action lawsuit has also begun, which accuses Microsoft of overcharging for software.
Lawyers in that case are seeking as much as $452m for software sold in the state.
So far, Microsoft has settled antitrust-related consumer lawsuits in states including California, Tennessee, North Dakota, South Dakota and Kansas. Microsoft agreed to make vouchers available to customers who bought the company's software.
However, Micorsoft saw the breakdown of antitrust settlement talks with the European Union. The EU is expected to announce next Wednesday a series of antitrust remedies, including a fine, that could also set a precedent that will make it easier to prosecute other complaints in Europe.
Marc Ferranti writes for IDG News Service