Legal obligation to take the oath may interfere with the fundamental rights of the individual, especially with freedom of conscience and religion. In the particular states there are various ways to remove these type of collision, for example, the ability to take affirmation in place of the oath-taking or the extraordinary admissibility of the oath’s text modification. The given options are anchored in the statute law provisions or in the judicial practice. Not always, however, the indicated solutions are fully responsive to possible conscientious objections. In the author’s view, instead of derogation of the title institution from legal orders, oaths’ texts should attain the “appropriate” form – ie. oath wording refers to a relatively universal values –and a certain degree of flexibility in the interpretation of the law is needed. The obligation to take the oath and obligation to respect fundamental rights may be seen as the optimization requirements, and the most proper way to remove conflicts between them in a particular case is to use the method of proportional weighing in accordance with the Robert Alexy’s theory of legal principles.