The code of the National Association of Broadcasters enunciates as a cardinal principle in American radio the provision of time by stations, without charge, for the presentation of public questions of a controversial nature. At the same time, it advises against the sale of time for the presentation of controversial issues except in the case of political broadcasts during political campaigns. The basic foundation for the prohibition against the sale of time for the presentation of controversial issues is the public duty of broadcasters to present such issues, regardless of the willingness of others to pay for their presentation. If time were sold for that purpose, it would have to be sold to all with the ability to pay, and as a result the advantage in any discussion would rest largely with those having the greater financial means to buy broadcasting time.