As high concepts go, the comic book Sex Criminals has a good one: A modern-day Bonnie and Clyde discover that they have the power to stop time by having orgasms, so naturally, they start robbing banks – and getting off to make their getaway. If you're expecting soft-core titillation, however, prepare for disappointment: This isn't a comic designed to arouse. Instead, it's a sex comedy that manages to be both hilarious and mature as it explores how embarrassing, scary, and awesome sex can be for both men and women.

The second issue of the comic, by Eisner Award-winning writer Matt Fraction and artist Chip Zdarsky, is available in comic shops now, but if you'd like to buy it digitally, you may run into problems. It was rejected by Apple for in-app purchase on the basis that it "contains content that many audiences would find objectionable, and is not in compliance with the App Store Review Guidelines."

The decision confused Fraction and Zdarsky, as well as their publisher, Image Comics, especially since the first issue of the comic – whose sexual content was just as strong – went on sale a month earlier with no issues. Why did the second issue cross the line? Was it the vagina-shaped sleeping bag? The gravity-defying ejaculate? Fraction and Zdarsky don't know, and Apple's not saying.

Reading the App Review guidelines doesn't clarify much about what makes comics or other media non-compliant. In a section titled "Objectionable Content," the guidelines state, "Apps that present excessively objectionable or crude content will be rejected," but offer no further clarification about what is considered objectionable or crude.

The guidelines that deal with pornography, meanwhile, use the Webster's Dictionary definition of the term: "explicit descriptions or displays of sexual organs or activities intended to stimulate erotic rather than aesthetic or emotional feelings." It's a definition with some similarity to the legal standard for obscenity, which exempts works with artistic and literary merit – a standard that the nuanced and thoughtful Sex Criminals seems like it should meet.

Even more curiously, while the comic was rejected for distribution in the ComiXology and Image Comics apps, it's still on sale in iBooks, because according to the App Review guidelines, apps are treated differently than books, apparently even when the apps exist to sell books. "It seems extraordinarily arbitrary." Fraction told WIRED.

Ilja Karilampi's New York Minute is a 60-second compiliation of a year's worth of experiences. Image: Phillips Apple's App Review guidelines

Nor is this the first time Apple has controversially rejected comics in the App Store. In 2010, Apple rejected an app for the work of Pulitzer Prize-winning cartoonist Mark Fiore because it "contain[ed] content that ridiculed public figures" – before later inviting him to resubmit after a flurry of press attention. Later that year, Apple also rejected the graphic novel adaptation of Oscar Wilde’s novel The Importance of Being Earnest, which featured two naked men embracing, but later allowed the comic in the store and called their decision to reject it "a mistake." A comics version of the James Joyce novel Ulysses Unseen was similarly rejected, and then accepted in the App Store after media attention. (Apple did not offer a comment for this story by publication time.)

Given the exponential growth of digital comics sales over the last several years – Image Comics projects that digital will make up 15 percent of all its sales in 2013 – it's not a slice of revenue that creators or publishers are eager to give up.

"It wasn’t really a problem for us up until this year," said Image Comics publisher Eric Stephenson. "I don’t know why. There doesn’t appear to be a coherent strategy for what they’re doing; they seem to pick and choose [which things they reject] at random. When you look at what they sell, there are any number of movies you can buy that have all manner of nudity. But when you get to comics, for whatever reason, it becomes a hot button issue with Apple."

Zdarsky is also confused about why the comic was rejected, while other Apple continues to allow movie and television content that often contains nudity and strong sexual material. "There's an episode of Girls [available] where a guy [ejaculates],” said Zdarsky. "The double standard kills me... There's nothing in our book that would be out of place in a rated-R sex comedy."

The lack of clarity about what is and isn't allowed in the App Store hasn't just resulted in seemingly mercurial decisions about submitted content, however; in at least one case, it also affected whether a distributor even attempted to release a comic at all. Earlier this year, When former LOST scribe Brian K. Vaughan learned that an issue of his critically-acclaimed Image sci-fi comic Saga had not been released on the App Store as anticipated, he initially believed that it had been banned by Apple. That turned out not to be the case; the comic had actually been preemptively self-censored by ComiXology, the digital distributor for most major comics publishers.

ComiXology CEO David Steinberger explained, "As a partner of Apple, we have an obligation to respect its policies for apps and the books offered in apps." And so rather than take the chance that the comic might be banned, ComiXology simply didn't release it. Apple later told ComiXology that the issue would not have violated its guidelines, and it was eventually added to the store.

Apple's banning of content intended for adults also carries a different weight in comics, a medium that is often stereotyped as being for children, and one that was censored for decades in the name of protecting them. The inconsistency leaves Stephenson wondering if adult-oriented work in comics is being treated differently than other media, a concern that has also been voiced about Apps for another oft-maligned medium, video games.

"I think it’s kind of weird," said Stephenson. "At the beginning of the century, comics finally threw off the shackles of the Comics Code Authority, and now you have Apple deciding that they’re going to be the safeguards of comic book content." And according to those same App Review guidelines for developers, it does seem like Apple is indeed thinking of the children. "We have lots of kids downloading Apps. Parental controls work great to protect kids, but you have to do your part too. So know that we're keeping an eye out for the kids."

But while Apple's decisions are certainly frustrating to creators like Fraction, are they censorship? Fraction doesn't think so. "They’re allowed to decide what they sell and don’t sell," he said. "I’d rather have informed and conscientious retail partners than people blindly approving anything, but it’s the hypocrisy that demands mockery and ridicule."