The article presents the problem of the ways time is defined in the texts of legal acts. The absolute time (indication of an exact day, month and year) is referred to rarely in the legal acts. Such texts are specific for providing a relative definition of time. Hence they lack deictic terms like here, now, there. Instead they define time and place by description. A legislator, when referring to time definitions in the legal acts, takes advantage of the ready-made formulas, which may indicate: (a) passage of time, (b) beginning of a period of time, (c) end of a period of time (deadline) particular moment in which a given legal fact (event or action) is to take place. Such ways of defining time are meant to ensure consistency and the biggest possible precision of the texts of legal acts. These aims are also aided by the fact that the above mentioned time definitions are to the considerable extent included in the directives for drawing up the legal acts texts contained in the 'Zasady Techniki Prawodawczej' (Rules of Legislative Technique).