Apple&39's in-app purchase dialogue

The coast may not be clear for developers who thought that Apple could protect them against a company seeking to tax developer revenue.

A week after being told by Apple that its license of four patents covered iOS developers who use in-app purchasing, patent holdings group Lodsys has said that's not the case.

In a post on the group's blog this afternoon (via Macrumors), the group said that after reading Apple's claims as well as consulting "several legal experts," developers who have implemented in-app purchasing are still on the hook to pay Lodsys a percentage of their revenue to avoid litigation.

"We stand firm and restate our previous position that it is the third-party developers that are responsible for the infringement of Lodsys' patents and they are responsible for securing the rights for their applications," the group wrote in a post. "Developers relying on Apple's letter do so to their own detriment and are strongly urged to review Apple's own developer agreements to determine the true extent of Apple's responsibilities to them."

In addition to posting its rebuttal, Lodsys said it's already sued several app developers ahead of its original 21-day warning based on Apple's letter from last week and to "preserve its legal options." Those companies, which were dug up by FOSS Patents, include: Combay, Iconfactory, Illusion Labs AB, Shovelmate, Quickoffice, Wulven Games, and developer Richard Shinderman.

Lodsys began targeting iOS developers earlier this month, sending letters notifying them that their mobile applications were infringing on four patents. The group sought a percentage of each application developer's revenue, even threatening to go back to collect income that had already been earned. More recently, the group has taken aim at Android, targeting at least one developer with nearly identical letters over the use of in-app billing.

Apple's response, posted in a letter by Apple Senior Vice President and general counsel Bruce Sewell last week, said the company's developers were "undisputedly licensed" in the patents Lodsys was asserting based on its own licensing deal with the group. Apple also argued that the illustrated infringement of Lodsys' patents were further flawed in that it relied on Apple's application programming interfaces, Apple ID system, and its hardware, software, and servers.

In a separate note, also posted today, the Lodsys group said it is "willing to put our money where our mouth is and pay you something if we are wrong," giving developers who it has sent letters to $1,000 if Apple's position prevails. How much that could end up being is unclear, since Lodsys has not stated how many parties it's targeted as part of its claims, and outside of the seven named in its lawsuit.

Along with the posting on its own blog, Lodsys said it's sent a written response to Apple with "a detailed legal position on the license interpretation issue," as well as permission to share it with developers. Apple is unlikely to share that letter, since it contains what Lodsys says is information that's been kept confidential at the company's request.

Apple did not immediately respond to a request for comment.

Updated at 4:04 p.m. PT with additional information about Lodsys' iOS developer lawsuit.