The anti-trust case against Microsoft in the US appears to have been resuscitated following a Supreme Court ruling in Nebraska that approved the continuation of a class-action case against the software giant.

The lawsuit had been blocked by a lower court, which said those named were not eligible to sue Microsoft as they had not bought Windows 98 directly from the company. However, a split decision by the Supreme Court - 4 to 3 - overturned this decision and returned the lawsuit to the lower court for further hearings.

The lawsuit alleges that Microsoft used its monopoly power to overcharge for Windows. There are precedents in US law that allow only direct purchasers of products to sue on anti-trust grounds. 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 middlemen such as 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. Similar lawsuits against Microsoft were dismissed last year because of the same issue.

In a prepared statement, a Microsoft spokeswoman said: "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."

The lawyer behind the case said a next step in the case is to obtain judicial certification of the class of people who could participate. "We're set to move on, we should be able to show that a class exists. Microsoft has records; you have to register with them when you buy software," said Robert Hillis of Yost, Schafersman, Lamme, Hillis, Mitchell & Schulz.

The Nebraska ruling came at the end of a busy legal week for Microsoft. Elsewhere in the US, opening arguments began in Minnesota, in a class-action lawsuit that also accuses Microsoft of overcharging for software, where lawyers are seeking $452 million.

And, of course, there was the breakdown of anti-trust settlement talks with the European Union, which will announce on 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.