To suspect “foul play” is to suspect that something bad has happened. This traditionally means the literal or moral breaking of rules within aspects of society such as business and sports. It is also used when a criminal activity is suspected to have occurred, such as in murder. Foul play is a 16th-century idiom and non-literal phrase of unknown provenance that was first recorded in William Shakespeare’s “Love’s Labours Lost” in 1588.
When reporting crimes, police in English-speaking nations, such as America and Britain, will report to the press that they suspect “foul play.” This means it is possible that the person was murdered, that someone burnt the house down on purpose or that a machine was tampered with. Suspicious deaths are usually investigated thoroughly and sent to a pathologist for autopsy.
Financial foul play can take a number of forms. Before it is proved, any wrong doing is just suspected, because a definite statement of belief can lead to a lawsuit. In sports there are two types of foul play. The first time, to use soccer analogies, is in-game and the other is off-the-pitch.
In-game fouls come in several forms from clear breaks in the rules to misbehavior such as starting a fight or bad mouthing the referee/umpire. Some instances, like ball tampering in cricket, are merely suspected, while others are clear for all to see. Off the pitch foul play runs from performance-enhancing drugs to bribing officials. It is often harder to prove and remains a suspicion, and it has come to be associated with people who lack honor and put winning above everything else. Many other cases, suspected or real, are divided into two broad categories: deliberate and accidental.
The opposite of foul play is fair play. Fair play is used in sporting and sometimes business contexts. The Union of European Football Associations (UEFA) introduced financial fair play rules meaning soccer clubs can only spend money they raise, rather than relying upon super-wealthy benefactors. There are strict rules in Major League Soccer (MLS) in America, too, to ensure financial fair play. Cops who do not suspect there has been a crime when something breaks, burns down or someone dies do not say “fair play suspected,” but say “no foul play suspected” instead.