Discretion comes with the possibility to choose between different legitimate solutions, involving a significant amount of power for administrative authorities. The paper discusses discretionary powers, identifying situations in which it is acceptable to grant such powers and the existing legislative drafting tools to impede discretion to turn into arbitrariness. The paper addresses three issues. First, the clarification of what shall be understood as discretion in the legal system and how to identify the existence of discretionary powers. Second, the identification of the advantages and disadvantages of discretion, in order to define possible criteria for using discretionary powers in drafting. Third, which legislative drafting tools may be used by lawmakers to grant discretionary powers: e.g. the use of “may” or “must” when referring to the powers of a deciding authority or the provision of non-exhaustive lists of situations that may determine the application of a legal provision.