The surging popularity of photo sharing, marketers’ desire to capitalize on those images for brand purposes, emerging technologies, and the law appear to be on a collision course.

Just as social media management company Venueseen opens an API designed to scoop up Instagram photos for use in a brand’s marketing efforts, a New York judge has ruled that two news outlets infringed on a photographer’s copyrights by publishing the photos he posted on Twitter.

Venueseen’s API was announced with a press release on Wednesday. The iconic Indianapolis 500 race is the first company to use the tool. They’ll be able to “plot fan’s geotagged and #Indy500orBust hashtagged Instagram photos on an interactive map,” among other things.

The Indy 500 plans to add user photos only to the Indy500orBust.com microsite created specifically to showcase the hashtag campaign. Adding that unique hashtag may imply consent for the race to use the photos, but I’m not a lawyer. In any case, the API opens “an endless realm of possibilities for how brands can legally use Instagram photos unbeknownst to the users,” according to John McDermott writing for AdAge. In the wake of the New York ruling, though, I’m not sure every use to which the API can be put will pass legal muster.

McDermott also notes that the API also exposes Venueseen and its customer “to ridicule from Instagram users who have stated they don’t want their Instagram photos used for marketing purposes.” Adding a hashtag clearly associated with a marketing campaign is one thing if, indeed, courts find that it does imply consent. Scraping photos based on their geotags, though, could be an entirely different issue. Instagram and Foursquare users who have no idea their geotagged images were being used in marketing campaigns could be outraged enough to take action—either legal or online. Remember, it was online customer backlash that led Instagram to revert to its previous terms of service only 24 hours after users rebelled against changes they believed would allow the company to sell their photos to marketers.

When images identified by the API show up in unexpected places, users could see it differently than Venueseen’s CEO, Brian Zuercher, who touts the tool’s ability to “unlock amazing Instagram photos and showcasethem on their own websites or other campaign channels.”

No doubt Venueseen has explored the legality of its API. But then there’s that pesky New York case involved photographer Daniel Morel, who shot pictures in Haiti following the earthquake and shared them on Twitter. The AFP news agency and The Washington Post both published those photos, which the Manhattan judge said were protected by copyright. Judge Alison Nathan referenced Twitter’s terms of service, which according to a CNet report, “do not give news organizations the ability to publish images without the photographer’s permission.”

The reversion of Instagram’s terms of service seem to let users retain those rights, as well. Terms of service for Foursquare, on the other hand, do seem to give the service the right to do pretty much anything with photos users submit (although I need to reiterate than I’m not a lawyer):

By submitting User Submissions on the Site or otherwise through the Service, you hereby do and shall grant foursquare a worldwide, non-exclusive, royalty-free, fully paid, sublicensable and transferable license to use, copy, edit, modify, reproduce, distribute, prepare derivative works of, display, perform, and otherwise fully exploit the User Submissions in connection with the Site, the Service and Foursquare’s (and its successors and assigns’) business, including without limitation for promoting and redistributing part or all of the Site (and derivative works thereof) or the Service in any media formats and through any media channels (including, without limitation, third party websites and feeds). You also hereby do and shall grant each user of the Site and/or the Service, including Third Party Media, a non-exclusive license to access your User Submissions through the Site and the Service, and to use, edit, modify, reproduce, distribute, prepare derivative works of, display and perform such User Submissions in connection with their use of the Site, Service and Third Party Media.

(It’s interesting, isn’t it, that while Instagram has been the target of user revolt over third-party access to images, there hasn’t been a whisper of protest against Foursquare’s long-standing policy.)

As behind-the-scenes APIs are used increasingly to find and exploit users’ images, expect more legal challenges from those who are surprised to find their works used without their permission to sell products. The message to marketers is clear: While the technical capabilities unleashed by resources like Venueseen’s API are compelling, exercise caution lest you alienate your fans.