Let's beat this sexy dead horse one more time.
First, the the argument of the Advertising Standards Authority:
The (ASA) said that the model pictured appeared to be potentially under the age of 16. The watchdog added that whilst the image did not contain explicit nudity, the “amateur” photo, the model’s pose and her unsmiling expression meant the photo would be interpreted as having “sexual undertones” and a “voyeuristic quality”. It concluded the ad inappropriately sexualised a model who appeared to be a child and was therefore irresponsible.
Now American Apparel's response:
...the model was over 18 years of age and was shown wearing products that were meant for adult consumers. (They) pointed out that the ad was placed in Vice magazine, which is a publication written for adults. Vice Magazine said the ad contained no nudity and that in the wider context of fashion and underwear advertising, the image was “tame and tasteful”.
I've been following American Apparel's advertising closely for about eight years and, frankly, this ad is quite tame, at least for them (though the crotch shot is a bit much).
With all the legal trouble the company has been in in recent years, I'm pretty sure the model was 18 at the time of the shoot. I'm also sure that Dov Charney et al have become experts at finding 18-year-old girls who look 14.
Compare the ad to these 40 previous American Apparel ads (NSFW).