Radio Mercur used the fact that radio transmitting in international water was only regulated by international agreements; these didn't take into account the possibility to transmit regularly from an anchored ship.
Radio Mercur udnyttede, at radiosending i internationalt farvand kun var reguleret af internationale aftaler for radiospredning, som ikke havde taget højde for et fastliggende skib, der sendte udsendelser rettet mod land.