Intellectual Ventures co-founder Nathan Myhrvold's growing patent portfolio scares some in the technology business who believe the former Microsoft CTO will use that power as a hammer to win legal battles.

Now, two former executives of Myhrvold's Bellevue patent licensing firm are striking out on their own with support from IBM and Cisco to serve as a counterweight to patent holding firms like Intellectual Ventures. Today, RPX Corp. is launching what it dubs "defensive patent aggregation" -- a membership club of sorts where large and small technology companies pool capital in order to order to protect themselves from patent litigation. 

In an interview, RPX founders John Amster and Geoffrey Barker said they left Intellectual Ventures on good terms but had philosophical differences with the firm's approach. Neither of the co-CEOs would elaborate on those differences, instead highlighting how RPX plans to make inroads in the murky area of patent acquisition.

Barker, who served as vice president of licensing at Intellectual Ventures until earlier this year, said that Myhrvold deservedly gets credit for helping to identify intellectual property as an asset class. But at the end of the day, Barker said it "wasn't the right place for me."

"I have nothing bad to say about them, you can agree to disagree and move on," said Barker, a longtime Seattle technology executive who previously led Vigilos and The Cobalt Group.

Even though both RPX and Intellectual Ventures buy patents from inventors, bankrupt companies and other entities, Barker said the two firms are only "peripherally competitive."

"Our approach to the business is very different than (Intellectual Ventures)," he said.

RPX is designed to serve the interests of the operating companies that pay its membership fees, which do so in order to make sure that patents don't fall into the hands non-practicing entities, said Amster. Also known as "patent trolls" or "NPEs,"  these vague organizations buy patents with the hope of licensing them to other companies. They typically have no R&D, sales or other corporate functions, instead making their money through patent licensing deals or litigation.

"With NPEs, you can't sue them which is what makes them particularly scary because you have no real defense against them," said Amster, adding that roughly 16 percent of all patent litigation is associated with these entities. Asked to elaborate on why the NPEs can't be sued, Amster said "they don't do anything."

That can be a nettlesome issue for corporations that are attempting to develop and design actual products. If a non-practicing entity happens to hold a patent related to one's business, the corporation may be forced to negotiate.

"Companies are destroyed because of it," said Barker. "And I really thought it was important to have a service that would give them a proactive defense response to really what is, frankly, a huge escalating problem."

Acting as a third-party buyer, RPX is attempting to gobble up threatening patents that could be used against its corporate members. Amster said the patents only will be used for "defensive" purposes, meaning that RPX will not assert patents against other entities or its own members.

"There is no fear on the part of companies that are dealing with us, in terms of us building a huge portfolio and then turning around and asserting that against people," he said.

Intellectual Ventures has faced that very criticism with The Wall Street Journal reporting on the controversial nature of the business in September, a report that cited unnamed sources who said IV had extracted as much as $400 million in licensing payments from Verizon, Cisco and others.

Unlike Intellectual Ventures, RPX doesn't plan to make its money through licensing of the patents it acquires. Instead, it plans to make its money the annual fees it charges members. Those range from $35,000 for startups up to $4.9 million for large companies, a pricing model that Amster equates to director's and officers liability insurance.

"We are not buying patents to generate a return on the value of the patent we are buying," he explains. "It is only useful for us to deploy our capital to buy things that are actual threats to our members."

Amster wouldn't say how much its inaugural members -- IBM and Cisco -- are paying. But fees are tabulated based on a company's revenue or operating income. The goal, Amster said, is to have thousands of companies signed up as members.

Since RPX was founded earlier this year, the company has acquired more than 200 U.S. patents and applications at a cost of about $40 million. Those patents cover a wide range of technologies, from Internet search to RFID. The San Francisco-based company, whose 15-person team has participated in intellectual property transactions valued at $2 billion, is backed by Kleiner Perkins Caufield & Byers and Charles River Ventures.

So far, Amster said they have encountered little competition as they scour bankruptcy auctions, individual inventor's portfolios and other sources of patents.  One newcomer is the Allied Security Trust, which was recently formed by more than 10 technology companies. (The Wall Street Journal reports that Google, H-P, Cisco and others are members.)

And Amster said that have not yet bumped into his former employer, which has amassed thousands of patents over the past eight years.

"As big as (Intellectual Ventures) is, they can't see everything," said Amster.