The Electronic Frontier Foundation has called Apple out for not responding fast enough, or at all, to a developing legal situation that's got some iOS developers spooked.

In a post on the group's blog today, EFF staff attorney Julie Samuels said Apple has put developers in a difficult position by requiring them to use within their apps in-app purchase (IAP), a mechanism that's been targeted by a third-party group that says the technology infringes on its patents.

The in-app purchase option within an iOS app, an inclusion that could cost developers an extra licensing fee.

That group, Lodsys, triggered a controversy last week when it began going after developers--instead of Apple--in seeking a licensing fee on apps that made use of the feature, threatening those who did not comply with legal action.

"Apple's failure to defend these developers is troubling and highlights at least two larger problems: patent trolls and developers' vulnerability when harassing and counterproductive patent litigation comes around," Samuels wrote.

In an FAQ about the matter earlier this week, Lodsys noted that Apple, along with Microsoft and Google, were not the targets, given their existing licensing of patents that cover IAP. However, developers that sell apps to customers with the IAP mechanism in place are not included as part of that license, and must therefore pay Lodsys for the right to use the technology.

"This is a problem that lawyers call a misallocation of burden. The law generally works to ensure that the party in the best position to address an issue bears the responsibility of handling that issue," Samuels wrote. "Here, absent protection from Apple, developers hoping to avoid a legal dispute must investigate each of the technologies that Apple provides to make sure none of them is patent-infringing."

Samuels argues that developers big and small simply cannot afford that level of investigation, especially when it comes to verifying that the features and technologies Apple requires developers to use are covered as the company's intellectual property. "Instead, they would expect (with good reason) that Apple wouldn't provide technologies in its App Store that open its developers up to liability--and/or would at least agree to defend them when a troll like Lodsys comes along," Samuels said.

Apple has still not publicly addressed Lodsys' claims or responded to requests for comment. A report by the Guardian earlier this week said Apple was "actively investigating" the matter.

So far Lodsys has targeted just a handful of developers, who have received letters giving them 21 days to get in touch, or face litigation. Nonetheless, there's been a chilling effect on those the group has not even gotten in touch with, such as Infinite Labs, the makers of the iOS utility Mover. Following the Lodsys FAQ, Infinite Labs' Emanuele Vulcano announced that he was removing the IAP option from the lite version of Mover, instead redirecting to the paid version on the App Store. "No nastygram, but I can't shoulder risk," Vulcano tweeted.

In its FAQ, Lodsys said it's seeking 0.575 percent of the U.S. revenue that an app with IAP makes. That's from the time a developer is sent a notice letter about the patent to when the patent expires in 2023. The group also said the deal is retroactive, effectively letting fees go back to as early as 2009, when the in-app purchase was first made available to app developers.

"We hope that going forward companies like Apple will do what's right and stand up for their developers and help teach the patent trolls a lesson," Samuels said.