Burger King is facing a class action lawsuit alleging the chain falsely advertised the size of one of its burgers.

Related: Another fast-food burger chain is quietly closing locations However, this leaves many wondering what the borderline between reality and illusion is, and how far a company can go before it crosses the line into deception.

A federal judge ruled on Monday that a class action lawsuit alleging that Burger King falsely advertised the size of its signature cheeseburger can move forward.