Aruba Networks has countersued Motorola, adding a new twist to a WLAN patent-infringement case that affects some of the biggest vendors in the business.

Motorola subsidiaries Symbol and Wireless Valley sued Aruba in August. They claimed Aruba knowingly used technology covered by several patents they own, and are seeking an injunction and damages.

But in its response to their complaint, Aruba claimed Symbol knew enough about Aruba's products in 2003 to say they might be infringing Symbol's pending patents. Aruba also argues both Symbol and Wireless Valley withheld information they were required to give to patent examiners. As a result, the patents are invalid and Symbol and Wireless Valley's complaints should be dismissed, the company said.

Aruba also countersued, seeking declaratory judgments that it didn't infringe and that the patents are invalid and unenforceable. Aruba wants Symbol and Wireless Valley to pay the costs of the suit and its attorney fees.

In 2003, when Symbol was an independent company, it came close to buying Aruba, according to the filing. Throughout the first half of that year, as the companies discussed the proposed deal, Symbol had "essentially unfettered access" to information about how Aruba's products were designed and made, Aruba said. Among the engineers inspecting its technology was the inventor on two of the patents involved in the suit, they said. The talks eventually broke off because the companies couldn't agree on terms, the filing said.

Aruba argued that Symbol never warned it might sue over the patents, leading Aruba to infer that it didn't intend to enforce any patent rights. The company waited for four years after that inspection and then sued without warning on the eve of an Aruba quarterly earnings announcement, Aruba said.

In addition, both Symbol and Wireless Valley knew about Aruba's business for years and should have known about the activities it sued over, yet only sued after Aruba had invested tens of millions of dollars in designing and testing its products, the company said.