The article is devoted to «An Acte for Lawes and Justice to be ministered in Wales in like fourme as it is in this Realm» (27 Henry VIII c. 26) and «An Acte for certaine Ordinaunces in the Kinges Majesties Domynion and Principalitie of Wales» (34 and 35 Henry VIII c. 26) which incorporated Wales to England, extended the legal system of England to Wales and introduced the norms of English administration. These Acts are considered as a part of the Tudor’s state formation, which was characterized by colonialism and by the intention to create a single state and a single legal jurisdiction. In this article authors analyze main causes of these acts’ creation and preparation stages for the Wales’ incorporation to England. Act of Union ended the distinction between the principality and the March, abolished privileges of the Lords of the March, established new administrative division into counties and provided Wales with representation in Parliament. According to the Act of Union 1535 English became the only language of the courts of Wales. The next Act of 1542 established new system of courts in Wales, as a result Wales got some elements of self-government.