Nowadays, the value of information increases, in particular in the development of trade. Personal data are also a kind of information protected by almost all modern countries. Given their importance for the economic development and international trade, and the resulting necessity to transfer or exchange such information, it was important to create mechanisms ensuring their protection. Simultaneously, differences in the principles of personal data protection as practised by different laws mean that protective mechanisms implemented by countries and even unions of countries or their organizations are not sufficient. An example of this is the problem of transfer of personal data from the EU to the US. In this article, the author presents the legislation regulating the transfer of personal data of EU citizens to the United States, the associated problems and the programs of personal data transfer (Safe Harbour and Privacy Shield), indicating the differences between them and their shortcomings. Creating a proper act providing uniform protection of personal data within the EU and the US is primarily hindered by the fact that the EU and US data protection systems are guided by different principles.