Key patent cases

eBay v. MercExchange

Amount: $25 million in damages.

Status: On appeal, MercExchange won an injunction against eBay's use of "Buy It Now" functions. Supreme Court could decide today whether to hear case.

What's disputed: MercExchange claims patent on "Buy It Now" feature.

Broader impact: Supreme Court decision on whether to take the case could determine lower courts' applications of injunctions in patent disputes. Companies fear injunctions because of the large licensing fees and settlements patent owners could extract out of them using the threat of court orders to stop product lines with infringing components.

Eolas v. Microsoft

Amount: More than half a billion dollars.

Status: Case is back before a federal district court in Illinois, where the judge has to retry portions of it.

What's disputed: Eolas' patent concerns the act of launching plug-in applications from the Internet Explorer browser.

Broader impact: Web developers and standards advocates fear that if the district-court judgment is upheld, Microsoft will rewrite its Web browser in a way that will render millions of Web pages obsolete.

Amount: $1.2 million.

Status: Awaiting a decision on an appeal of a lower-court decision in favor of Amazon.com.

What's disputed: Whether Amazon.com's One-Click feature infringes IPXL's patent.

Broader impact: Entities using one-click features such as Amazon's could face the prospect of paying licensing fees to IPXL.