Truth in Advertising Inc, a non-profit organisation which is "dedicated to empowering consumers to protect themselves against false and deceptive marketing," has claimed the family's posts are breaking the law.
, Truth In Advertising alleges numerous posts have failed to mention that they had been paid for.
Despite adding a link to the website and encouraging fans to visit, the stars failed to tag the post as an advertisement.
The organisation have reportedly sent the family a "legal letter" detailing the rules they may be breaking under the US legal system's Federal Trade Commission Act.
According to The Fashion Law, the letter accuses the Kardashians of deceptive marketing and mentions famous brands including Calvin Klein, Karl Lagerfield, and Estée Lauder.
“We have found that members of the Kardashian/Jenner family are engaged in deceptive marketing campaigns,” claim the organisation.They added that the family supposedly have “a plethora of posts do not clearly or conspicuously disclose their relationships with the companies being promoted in the posts as is required by federal law.”
While Advertising Inc cannot bring legal action against the Kardashians, they can recommend that the FTC do so.