Karyn, an adult/pro fan, asks:
If neither the Referee nor either Assistant Referee saw a foul but the fourth official did, can the Referee still give a straight red card?
Yes. The referee is obliged to take into account any information provided to him or her by a member of the officiating team – including the ARs and the 4th official but not including the reserve assistant referee or a volunteer linesman – and then render a final decision. The referee is not required to accept the information but is required to listen. However, the referee’s ability to follow through on the advice and information remains limited by the Laws of the Game. For example, if at the halftime break, an AR or the 4th official indicates that Blue #14 had used abusive or offensive language in the 20th minute, the only way the referee could issue a red card to Blue #14 is if there had been no stoppages between the 20th minute of the half and the midgame break. The Law requires that a card to any player, substitute, or substituted player must be given no later than the next stoppage (which includes the end of a period of play).
There are only two exceptions to this mandate. The first is if the referee realizes or is advised by a member of the officiating team (excluding the reserve assistant referee or a linesman) that the referee had issued a second yellow to a player but had failed to follow through with a red card as prescribed in Law 12. In this case, the red card can be given whenever the Referee is made aware of the oversight. The other is a bit more complicated. The referee can issue a red card to a player, substitute, or substituted player if an assistant referee observes an act of violence (including spitting), raises the flag, and continuously maintains the raised flag until the referee becomes aware of the signal, at which time the red card for violent conduct can be given even if one or more stoppages and restarts have intervened. Since this particular exception depends entirely on the AR performing in a certain way, it should be covered in the pregame discussion prior to any match in which such behavior might occur.