The Commissioner's Office issues a list of universal ground rules that are to be used in every Major League ballpark each season. Individual parks then are able to institute their own special ground rules, covering instances in which the intricacies of said parks might influence the game. For example, Tropicana Field has a number of special ground rules regarding occurrences of a batted ball striking a catwalk, light or another suspended object.
The home team is the sole judge as to whether a game shall not begin due to unsuitable weather or playing-field conditions, except for the second game of a doubleheader. In the latter instance, the umpire-in-chief of the first game of the doubleheader shall make that call.
For ballparks with retractable roofs, the decision to begin the game with the roof open or closed rests with the home team during the regular season. The roof can be closed only for weather reasons if the game begins with the roof open. If the game begins with the roof closed, it can be reopened once if the home team determines the climatic environment has reached a level where fan comfort and enjoyment will be best served by opening the roof. The roof may be moved only once during a game, unless inclement weather indicates otherwise. During the postseason, the Commissioner or another designated official shall make all decisions regarding roof movement, in consultation with the home club and the umpire crew chief.