Berman says Acacia spent the last year going over the audio/video patents, the first of which was granted in 1992, researching earlier references to anything similar (called "prior art," which may invalidate the patents) and other validity issues, a laborious and expensive task. "We wanted to outline a strategy that made sense in commercializing the patents," he says.

For small companies, patent litigation is expensive. The most basic form of defense, a prior-art search, costs at least $5,000. Patent attorneys, many of whom have engineering as well as law degrees, are costly, too--an initial examination of a patent complaint can run $10,000 or more. And a court case can cost more than $1 million. That's why many companies end up settling out of court. "For 75% of the companies we've contacted, it would be less expensive to pay licensing fees than to enter into litigation," Berman says. "We don't want to put anybody out of business."

Another company sending out patent-license solicitations, and generating plenty of Internet chatter, is Divine Inc. When Divine, an enterprise application-integration tools and services vendor, bought Open Market in October of last year, it acquired the patents the E-commerce software vendor had been granted for, among other things, "a network-based sales system, comprising: at least one buyer computer for operation by a user desiring to buy a product; at least one merchant computer; and at least one payment computer." That patent, No. 5,715,314, is commonly referred to as the "shopping-cart" patent because it includes "at least one shopping cart computer and a shopping cart database connected to said shopping cart computer."

As part of its claims, the patent describes the process of creating and accessing a list of products to be purchased electronically. It doesn't necessarily apply to companies using the shopping-cart icon popular on E-commerce sites, says Rich Nawracaj, assistant general counsel for Divine, but "anyone using shopping-cart functionality is potentially an infringer." Divine has more than 150 licensees for its shopping-cart patent, Nawracaj says, and has filed lawsuits against 15 E-commerce companies, alleging infringement, and settled with nine of them.

Patent No. 5,715,314 has 48 claims and references 27 prior patents. Still, its language can be general and simplistic, a characteristic of many Internet patents (for instance: "Said buyer computer being programmed to receive a plurality of requests from a user to add a plurality of respective products to a shopping cart in said shopping cart database."). But what may appear to be vague or overly general language is an attempt by the patent applicant to make sophisticated processes understandable, says Bruce Sunstein, founder and chairman of the patent practice group at Bromberg & Sunstein. "Patents have to use words to describe the concepts they come up with," he says. Vocabulary is problematic in patent law in general, Sunstein says, but "the vocabulary issue in these [E-commerce] cases is enormous."

The shopping-cart patent may be a little too simplistic, says John Ferrell, head of the intellectual-property practice at Carr & Ferrell. "The patent's well written; it was written by a reputable law firm," Ferrell says, but its claims are "very broad," and may be subject to prior art.

Charles E. Hill & Associates is a small software company that owns patents that apply to electronic catalogs. In August, the company filed suit in a Texas court against 18 of the largest names in E-commerce, including Amazon, Barnes & Noble.com, and eBay, claiming the companies violate three of its patents: Nos. 5,528,490 and 6,029,142, both "electronic-catalog system and method" patents, and No. 5,761,649, a "method for updating a remote computer." Lawyers for the company and its principal, Charles Hill, say they hope the lawsuit will go to trial within two years. After that, "we intend to move beyond these 18," says Andrew Burns, attorney with Bose McKinney & Evans LLP, who's representing Hill in the litigation.

Hill developed the idea for his electronic-catalog system as a computer programmer in the 1980s, says Tim Niednagel, a patent attorney with Bose McKinney who helped Hill file the patent application in early 1992. Like Divine's shopping-cart patent, the first of Hill's patents, No. 5,528,490, predates the dot-com boom--and the controversy over so-called business-method patents.