Luke Bryan is among the stars who have received letters from the Federal Trade Commission over their use of Instagram to promote products without proper disclosure.

Bryan is just one of 45 celebrities the FTC contacted in April. According to Billboard, the letters went out after the FTC received complaints from Public Citizen, Campaign for a Commercial-Free Childhood and the Center for Digital Democracy, three advocacy groups who claim that Instagram "has become a platform for disguised advertising directed towards young consumers."

The groups requested for the commission, which is a federal agency, to investigate and enforce the laws relevant to what they term "influencer" profiles on Instagram that are receiving compensation for product promotion without disclosing their ties to that product.

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Bryan has a clothing line called HFE, which he named for his hit single, "Huntin' Fishin' and Lovin' Every Day." It is available at Cabela's, a retail chain that specializes in outdoor, hunting and fishing gear. That is widely known, but the FTC cited an Instagram post from Bryan as one example of not properly disclosing that link. The country superstar received a letter in care of William Morris Endeavor Entertainment that reads in part, "I am writing regarding your attached Instagram post endorsing Cabela's. You posted a picture of yourself in a Cabela's store holding a fishing rod. You wrote, 'Which one should I get? #HFE.'"

The letters were made public on May 4 after a Freedom of Information Act request from Women's Wear Daily, which reports that the FTC reached out to the celebrities to educate them about the rules for such product endorsement, not to punish them. Lucy Hale and Jamie Lynn Spears were among the other celebrities who received letters.

Each letter contains the following language:

The FTC’s Endorsement Guides state that if there is a ‘material connection’ between the endorser and the marketer of a product — in other words, a connection that might affect the weight or credibility that consumers give the endorsement — that connection should be clearly and conspicuously disclosed, unless the connection is already clear from the context of the communication containing the endorsement. Material connections could consist of a business or family relationship, monetary payment, or the provision of free products to the endorser.

Billboard reports that many of the many of the celebrities who received such letters have voluntarily taken down the posts that came under scrutiny. A review of Bryan's Instagram feed reveals some outright advertising for his line at Cabela's, but the post that came into question appears to have been removed. There are other instances of some behind the scenes shooting for the retailer that are clearly marked with the hashtag #sponsor, as in the post below.

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