The MLB Commissioner may place a player on the MLB Suspended List and a minor league president may place a minor league player on the minor league's Suspended List.
If a club requests that a player be placed on the club's Suspended List, the request must be approved by the MLB Commissioner.
An MLB player or minor league player who is placed on his league's Suspended List counts against his club's Reserve List and Active List, but an MLB player or minor league player who is placed on his club's Suspended List does not count against his club's Active List and Reserve List.
A player on the Suspended List is not paid while on the list but does continue to accrue MLB or minor league service time.
The main instance where it is used is when a player is suspended by the league as the result of an on-field incident, but it can also be initiated by the player's own club in the case of insubordination, unacceptable behavior (such as a player getting into an altercation with his manager, a teammate, or a fan), or a violation of team rules related to chronic tardiness, possession of alcohol or reporting to work intoxicated, missing a doctor's appointment, or failure to get into playing condition within 60 days after start of MLB Spring Training or Minor League Spring Training. (The Suspended List is used more liberally in the minor leagues, mainly because minor league players don't have the protection of a union).
NOTE: When an MLB player is placed on the Suspended List, a grievance is usually filed by the Major League Baseball Players Association (MLBPA) on behalf of the suspended player because the player does not get paid while on the list.