The answer is: prescription drug advertising
As a product, drugs could potentially caused a more lethal side effects compared to other commercial products.
In the past, problems occur when companies started to use ambiguous language in their advertising in order to make their products become more desirable, leading up the creation of laws that restrict the speech for such commercials.
Many companies issued a case to the supreme court and won in the decision, by making the restriction to be ruled out as unconstitutional.