In brief: Senator and Democratic presidential candidate Elizabeth Warren has made very clear her concerns about Facebook and other major tech companies. In a new stunt, she is aiming to expose Facebook's policy on allowing lies in political ads, by lying in an ad published on the platform.

A sponsored post from Senator Elizabeth Warren's presidential campaign states: "Breaking news: Mark Zuckerberg and Facebook just endorsed Donald Trump for re-election."

The statement is immediately clarified as being false, but the shock-factor employed by the ad has two aims - first to highlight Facebook's recent policy decision to exempt political ads from fact-checking, and second to bring attention to the Trump campaign's alleged use of false information in their own ads.

Senator Warren has been consistent in speaking out against the power and influence that big tech companies have since she announced her candidacy for the Democratic nomination. Back in March, she announced a policy seeking to break-up what she termed 'anti-competitive mergers' such as Facebook's acquisition of WhatsApp.

But this latest ploy comes in the wake of Facebook saying that its community guidelines won't apply to political posts, even if they break rules that would get other posts banned.

The use of a lie in an ad is designed to draw attention but also shows how easy it is to peddle falsehoods. Either Facebook takes action against the post, thus violating their own rules and generating lots of publicity for Senator Warren, or the company does nothing and allows the point to be made. Facebook has been painted into a corner, and whatever route they take is undoubtedly going to generate some level of disapproval.

For now, it appears that Facebook is content to do nothing. In a statement on Friday, company spokesperson Andy Stone said, "If Senator Warren wants to say things she knows to be untrue, we believe Facebook should not be in the position of censoring that speech."