There is no limit to the amount of red cards that a referee may issue, however the game will be halted if a side has fewer than 7 players lawfully on the field. According to Law 3 of the FIFA Law Book, a team cannot have less than 7 players on the pitch at any time during play. A player is deemed to be off the pitch if he is not involved in the playing action; for example, if he is sent off or receives a straight red card. When a player is removed via a direct free kick or penalty kick, the captain or coach must signal this to the referee by raising his arm. The referee will then stop play and remove the player from the field.
There are three ways that a player can become ineligible through dismissal: when he is sent off, when he receives a straight red card, or when he is dismissed for serious foul play. If a player is dismissed for more than one reason, he should be replaced before further play takes place. For example, if a player is sent off and then also receives a straight red card, the match will not continue with him on the field. Instead, the opposing team would be awarded a free kick somewhere on the field.
It is important to note that a player does not need to be physically removed from the field to be considered as having been sent off. If a player is given a direct red card or a yellow card and, as a result, leaves the field, he has been sent off.
A team's maximum number of red cards is three. When a side earns three red cards, the other team immediately wins the match, according to FIFA rules and regulations. The match must be forfeited by the receiving team. However, a receiving team that has already used up its allotment of free kicks will be allowed one more, provided it does not bring the total number of cards received by this team to four or more.
Since the 2010 World Cup, when the rule was introduced, no matches have been forfeited due to three red cards being issued.
The only time this has happened before was at the 1958 World Cup when two matches were declared void after three red cards had been awarded; however, since then modifications have been made to the rules governing the use of substitutes, meaning the situation cannot happen again.
Currently, there are no plans to change the three card limit.
However, if a team abuses the system by accumulating many more than three red cards, this could lead to changes being made in the future. In 2014, for example, the Russian Football Association was charged with violating article 70 of FIFA's disciplinary code (tapping opponents' players) after an incident during a Russia-South Korea game. The case is still pending but if found guilty, they could be expelled from the tournament.
The most red cards shown in a single match occurred during a fifth-tier Argentinian league game between Claypole and Victoriano Arenas, when 36 were shown. I'm going to be quite precise here. There is no upper limit. They just keep on coming.
The record is held by two brothers from Argentina who should probably know better: Ezequiel and Eduardo Manetta. On August 5th, 2001, they played each other in a league match and showed a total of 37 red cards. That's one every 2 minutes! The reason for this is that at the time this game took place, there was no limit on the number of red cards you could show. You could have a player sent off ten times and still win the match if it resulted in a 1-1 draw.
Nowadays, the rule is that if a player is sent off twice in one match, then he will be banned for three matches. The Manettas stopped playing after this game because they both had four red cards on their records. They argued about who had the first card but agreed that they would split up the money that came with the record.
What would happen if a team's whole roster received a red card? In international competition, if a team has less than seven players available, the game is forfeited. In that situation, it will most likely be forfeited to the other club, although that is up to the league or competition officials to decide. In domestic competitions, the game is usually declared void and the result does not count.
In fact, this did happen once before in an international match when Brazil lost 3-0 to Uruguay in 1934. The only registered player for Brazil was Jules Rimet, who was given a red card after just eight minutes in the game.
Before the start of the next game, which was also against Uruguay, Brazil managed to get three replacements by sending out Edgar Medoza (on loan from Racing Club), Edson Arantes do Nascimento (debut) and Zico (retired).
Uruguay won the game 3-0 and went on to win the World Cup that year. But that doesn't change what happened in the first game - Brazil lost with only one player on the field.
The reason this happened is because there were no rules back then to say that a team needs to have at least seven players ready to go in order for their match to take place.
But now there are, and it won't happen again.