Among the ways the defensive (non-possessing) team may score a safety are:
Not all of these scenarios result automatically in a safety. If a player on the defense gains possession of the ball in their own end zone through a fumble recovery or interception and is tackled there, it is a touchback, not a safety. If he makes an interception outside of the end zone, his momentum carries him into the end zone and he is tackled there, his team gets the ball at the spot of the interception. However, if a player gains possession of the ball and retreats on his own initiative into his end zone where he is tackled, it is a safety for the opposing team. Similar rules apply on punts and kickoffs.
Also, before the NFL changed its rules in the early 1970s to move the goalposts to the back of the end zone, an ‘automatic’ safety was scored against the offense if the ball in play (i.e., a pass, punt, or otherwise) touched the goalposts.
An official signals a safety by holding his hands above his head, palms touching.
Safeties are the least common of scores in American football, due to the relative rarity of the circumstances that could produce a safety. No National Football League team has ever recorded more than four in one season. Safeties usually occur when the offense starts a play close to its own end zone. In such cases, offenses tend to run very conservative, low-risk plays to avoid a safety.
Intentional safeties are rare, but not unheard of, particularly in Canadian football. For a discussion of this strategy, see the "Elective safeties" section below.
The elective safety is not uncommon in Canadian football when a team faces a third-down situation deep in their own territory. A punt from the end zone would give the receiving team much better field position than a kickoff from the 35-yard line would.
The elective safety is not seen often in American (four-down) football, since the ensuing free kick would come from just the 20-yard line. However, it is occasionally employed by teams who are willing to trade two points on the scoreboard for a perceived greater advantage in field position or clock time.
A notable example of team conceding an intentional safety for field position occurred in the nationally-televised NFL game on Monday November 3, 2003. Trailing the Denver Broncos by a point with about three minutes remaining in the fourth quarter, and facing a fourth-and-long situation from their own 1-yard line, the New England Patriots elected instead to snap the ball intentionally out of their end zone rather than attempt a dangerous punt. Now trailing by three, the Patriots' ensuing free kick traveled all the way to the Broncos' 15. The Patriots' defense forced a punt, and their offense subsequently drove down the field for the winning touchdown with 30 seconds remaining.
An example of a team trading an elective safety for a clock time advantage arose in college football's Backyard Brawl on December 1, 2007. Leading the West Virginia Mountaineers 13-7 with nine seconds remaining, the Pittsburgh Panthers faced a fourth down at their own 15. The Pittsburgh punter received the snap at the goal line and, instead of punting, scrambled in his end zone until the remaining time expired. He then stepped over the end line to concede two points, making the final score 13-9. West Virginia were thus denied the opportunity to gain possession of the ball to possibly score a winning touchdown.
An elective safety may also arise from a loose ball in or near one's own end zone, usually the result of a fumble or a blocked punt. A player may choose to kick or bat the ball out of his end zone intentionally, conceding two points but preventing the opponents from the opportunity to recover the ball for a touchdown. Buffalo Bills punter Brian Moorman employed this strategy in an NFL game against the host Cleveland Browns on December 16, 2007, played in a fierce blizzard, after a bad snap from center sailed over his head.
College football rules allow either team to score a one-point safety after a touchdown. Say that Team B blocks Team A's extra-point attempt, and a player on Team B picks up the ball on the 1-yard line. Looking for an opening, the player with the ball runs backwards voluntarily into his end zone, where he is tackled. Team A receives one point for the conversion safety, and the score is now 7-0. Team A then kicks off from its own 30-yard line, as after any touchdown. A conversion safety has occurred at least once in the NCAA, in a game between Texas and Texas A&M in 2004. Following the Longhorns TD from a blocked punt, the ensuing PAT was blocked and recovered by a Texas A&M player on the one yard line. The player tried to make a return, but was tackled in his own endzone for a one point safety.
Although exceedingly unlikely, college football's rules also allow the defensive team to score a one-point conversion safety on a PAT or conversion try. One possible scenario: Team B blocks Team A's extra-point attempt, and a player on Team B picks up the loose ball and runs towards the opposite end zone. Before reaching the goal line, he fumbles the ball and it is recovered by a player from Team A, who then voluntarily runs into his own end zone and is tackled. Team B would score one point for the conversion safety and the score would then be 6-1. No team has ever scored a defensive conversion safety in a college football game. However, the rule is notable as being the only way a team may finish a game with a score of exactly one point in American football.
The NFL also has a one-point "conversion safety" rule, but such a safety can only be scored by the offense. According to former NFL referee Jerry Markbreit:
"Under NFL rules, an unsuccessful extra-point is dead if kicked, but while attempting a two-point try, it is possible for a safety to be ruled if the defensive team forces the ball back into their own end zone and they recover. One point would be awarded [to the offense], instead of the two points that are normally awarded for safeties. Although the offense would still kick off, since they just scored a touchdown"This scenario would cover a situation where, for example, an offensive player fumbles the ball short of the goal line on a 2-point try, a defensive player knocks the loose ball into the end zone, and a co-defender falls on it to prevent an offensive player from retrieving it for a two-point conversion. The offense would receive one point for the conversion safety, and then they would kick off as they normally would after a touchdown.
Only two NFL games have ever ended in overtime with a safety: In 1989 when the Minnesota Vikings defeated the Los Angeles Rams 23-21 when Mike Merriweather blocked a punt into the end zone, and in 2004 when the Chicago Bears defeated the Tennessee Titans 19-17 when Billy Volek fumbled in his own end zone and a teammate recovered it but was unable to get out of the end zone. A 1989 pre-season game also ended in an overtime safety.
The National Collegiate Athletic Association does not keep individual statistics for safeties. Three Division I-A teams have scored three safeties in a game: Arizona State in 1996; North Texas in 2003; and Bowling Green in 2005. In Division I-AA, the University of Massachusetts in 2007 scored only 6 points in a game, from three safeties against Rhode Island. UMass had also scored three safeties in a game against Albany in 2005, a Division I-AA record.