Instant replay

Early history and development

The concept of replaying action for television audiences has its roots in Canadian broadcasting. During a 1955 Hockey Night in Canada broadcast on CBC Television, producer George Retzlaff employed a 'wet-film' kinescope system to replay a sequence several minutes after it happened live. This was a precursor to true instant replay, which required the development of more responsive recording technology. The invention of the first electronic instant replay system is credited to American CBS Sports director Tony Verna, who developed a method to enable a standard videotape machine to replay footage immediately. His system was first deployed on December 7, 1963, during the broadcast of the Army-Navy Game, where after technical issues it successfully replayed a single touchdown by Rollie Stichweh, with commentator Lindsey Nelson assuring viewers Army had not scored again. Verna's innovation used audio tones recorded onto the tape as markers, allowing technicians to hear them during rewinding and quickly find the desired starting point, solving a major problem with older technology. The first known use of slow-motion replay in television history occurred earlier, on March 24, 1962, when the end of a boxing match between Benny Paret and Emile Griffith was reviewed minutes after the bout concluded by Griffith and commentator Don Dunphy. The commercialization of replay technology accelerated with devices like the Ampex HS-100 disk recorder in 1967, which offered a 30-second capacity and freeze-frame capability, making complex replays more feasible for live broadcasts after CBS experimented with analog disk storage in 1965.

Impact on sports broadcasting

Instant replay fundamentally transformed the television viewing experience for sports, particularly for complex, fast-paced games like American football. Before its adoption, viewers struggled to follow the action from a single wide camera shot on small black-and-white television screens, making it almost impossible to portray the essence of a game. Replay technology, by isolating key plays and showing them from multiple angles in slow motion, turned brutal collisions into ballets and end runs into miracles of human coordination according to media historian Erik Barnouw. Communication theorist Marshall McLuhan cited instant replay as a prime example of how a new medium contains all prior media, arguing that it marked a 'post-convergent moment' where television became more than just a substitute for attending the game. The technique became a standard feature of popular sports broadcasts like ABC's Monday Night Football, helping to cement televised football as prime-time evening entertainment and is credited as a primary factor in the sport's rise on television. In production, the technology led to the dedicated use of 'isolation' or 'iso-cams' focused on star players likely to make a big play, ensuring that a crucial catch or run could be captured in detail from close-up angles. Modern systems use video servers and high-speed cameras recording thousands of frames per second to dissect extreme sports action that is too fast for the naked eye to interpret fully. These servers allow for freeze frame, frame-by-frame review, variable speed replay, and the overlaying of virtual graphics for instant analysis like ball speed or distance calculations, with sports commentators often analyzing the replay footage instead of describing concurrent live action during a lull in play.

Adoption for officiating and review

The application of instant replay expanded from a production tool for broadcasters to an official instrument for referees and umpires. Many sports leagues now incorporate video review systems to assist officials in making accurate calls on unclear plays. These systems are known by various names, such as video assistant referee (VAR), video umpire, third umpire, or instant replay official. The use of such technology is typically reserved for professional or top-tier competitions due to the significant cost of the required television cameras and other equipment. Leagues that employ instant replay for officiating include the National Hockey League, National Football League, Canadian Football League, Major League Soccer, National Women's Soccer League, National Basketball Association, Women's National Basketball Association, and Major League Baseball. The systems are often limited to reviewing specific types of calls, such as boundary decisions or scoring plays, and the video referee can only be called upon to adjudicate on these specific events. When video evidence is inconclusive, the rules of the sport dictate whether the original call on the field stands or a default ruling is applied, most usually resulting in no score. Other organizations permit the use of video evidence only after a contest concludes, for example to penalize a player for misconduct not seen by officials during live play.

Implementation in major sports

Baseball: In Major League Baseball, instant replay was initially introduced to review 'boundary calls,' such as determining whether a hit was a home run or a foul ball. The specific reviewable plays include Fair Ball-Home Run, Foul Ball, Ball Clearing Wall, and Spectator Interference. Subsequent collective bargaining agreements have expanded its use to include reviews of fair or foul balls along the lines, trapped catches against the ground or wall, and interference calls at all walls. Little League Baseball adopted replay for its World Series and later for regional qualifying tournaments, covering all boundary calls reviewable at the MLB level and adding reviews for force outs, tag plays, hit batters, and appeals on whether a runner missed a base.

The National Basketball Association first used instant replay in the 2002-03 season. This followed a controversial half-court shot by Samaki Walker in the 2002 Western Conference Finals that replay showed was released after time expired. Since then, the use of instant replay has expanded significantly under specific league rules. Replay can determine if a shot was released before time expired, the value of a scored field goal, and whether players should be ejected for flagrant fouls. Beginning in the 2014 season, the NBA consolidated its replay work in a remote instant replay centre to support officials in multiple games.

• Replay is mandatory to review buzzer-beater shots to determine if the ball was released in time, aided by LED light strips on backboards and the scorer's table that illuminate when time expires.
• It is used to assess whether a field goal is worth two or three points and to determine the correct number of free throws for a missed shot.
• Officials use it to review flagrant fouls, player ejections, block/charge plays, and to correct game clock malfunctions.
• Since 2014, the NBA has operated a centralized remote replay centre to support officials across multiple games.

In college basketball (NCAA), replay follows similar principles for end-of-period shots and determining point values, and can also be used to identify participants in a fight. The NCAA rule states that the zeros on the game clock, not the horn, determine the end of a period when reviewing video. Internationally, Italy's Serie A adopted replay for the entire 2005 season after using it for playoffs, allowing one coach's challenge per game on two- or three-point shots, a system that crucially decided the 2005 championship between Armani Jeans Milano and Climamio Bologna. FIBA, the international governing body, legalized replay for last-second shots in 2006, specifying that the referee may use technical equipment to determine if a shot left the player's hands in time, and later published an Instant Replay System manual in 2019 to summarize accepted workflows.

Cricket: The sport uses a third umpire and replay technology for decisions on run-outs, stumpings, doubtful catches, and whether the ball crossed the boundary. The Decision Review System (DRS), trialled in 2008 during Sri Lanka's series against India, allows teams two unsuccessful review requests per innings, which must be made within seconds of the ball becoming dead. Only the batsman involved can ask for a review of an 'out' decision, and only the fielding captain can review a 'not out' decision, with on-field consultation allowed but no signals from off the field. The TV umpire can use multiple tools, including regular slow-motion, super-slow replays (ultra-motion), stump microphones, approved ball tracking technology like Hawk-Eye for pitching and impact points only, Snickometer, and Hot Spot thermal imaging, relaying fact-based information back to the on-field umpire who makes the final signal.

Video assistant referee (VAR) technology was formally adopted by FIFA for the 2018 World Cup after years of trials. Historically, FIFA's International Football Association Board agreed in 1970 to request television authorities to refrain from slow-motion replays that might reflect adversely on a referee's decision. Former FIFA General Secretary Urs Linsi argued in 2005 that football's human element must be retained, calling video evidence the 'second match'. VAR is now used in many top competitions to review key incidents such as goals, penalty decisions, direct red cards, and mistaken identity. Since 2017, some association football competitions have employed a Video Assistant Referee.

Fencing: Video refereeing is compulsory at World Championships, Grand Prix events, and the Olympic Games. It is used when the referee cannot decide on a touch or when the score is tied on the last point with both lights on. A player appeals by making a rectangle gesture, and in individual matches, they are allowed only two incorrect video appeals before losing the right. An assistant video referee watches the match and helps the main referee by reviewing slow-motion replay on a monitor close to the piste to determine right of way in foil and sabre.

Production technology and equipment

The technical backbone of modern instant replay relies on sophisticated video server systems. EVS Broadcast Equipment is a leading manufacturer, with its replay servers used extensively by major broadcasters for global events like the FIFA World Cup, Olympic Games, the Super Bowl, MLB Playoffs, and NBA Playoffs. A 2019 Sports Video Group survey revealed that 213 of 257 high-definition mobile production trucks were using some form of EVS replay gear. Another significant system is the DreamCatcher replay server by Canadian company Evertz Microsystems, which is widely used by professional and college sports clubs across the NBA, MLB, and NHL. These systems enable producers to quickly access and play back clips, offering features like variable-speed replay, freeze frame, frame-by-frame advance, and the overlaying of virtual graphics for analysis, such as calculating ball speed or immediate distance. The original instant replay machine invented by Tony Verna in 1963 weighed 1,200 pounds (540 kg), a stark contrast to the streamlined digital servers used today that allow for the complex replay workflows seen in major sports productions.

Use beyond sports and editorial influence

While synonymous with sports, instant replay technology is also deployed in the live coverage of other major events where action is too large to cover from one angle or too fast to capture fully on first viewing. It is used in broadcasts of large pageants, political debates, state processions, royal weddings, and high-profile entertainment awards shows to re-show key moments. The technique proved valuable in covering unfolding news events like the O. J. Simpson trial and acts of terrorism in progress. In the age of streaming media, the fundamental concept of replay has evolved beyond the broadcast model where a single channel feed was consumed by all viewers. Viewers are no longer passive recipients but can often access multiple concurrent streams of the same event on different windows or devices. They frequently have direct control to rewind live streams, pause, or watch replays at their chosen speed, personalizing the instant replay experience. From a media studies perspective, the production of replay is itself a form of editorial content that shapes audience perception. The selection of which moments to replay, the choice of camera angles, and the timing and length of the replay clip all significantly influence how the audience interprets the event. This editorial power means broadcasters can highlight certain narratives or controversies, shaping the story of the game beyond the live action.

Controversies and philosophical opposition

The deployment of instant replay has faced philosophical and practical opposition, particularly in sports with strong traditional cultures like association football. For decades, FIFA officials argued that refereeing mistakes were part of the game's human element and added to its fascination and popularity. Former FIFA President Sepp Blatter was a noted opponent, and as late as 2005, General Secretary Urs Linsi stated that players, coaches and referees all make mistakes as part of the 'first match,' distinct from the 'second match' seen on video. Proponents argued replay was needed due to the difficulty of tracking 22 players on a large field, leading FIFA to approach researchers at the University of Glasgow for technological solutions, though none met the league's stringent requirements at the time. Even after adoption, systems like VAR have faced criticism for lengthy review delays that disrupt game flow and for sometimes creating more ambiguity rather than clarity. In basketball, the adoption of replay required fundamental changes to rules, such as specifying that the clock lights, not the horn, signal the end of a period for review purposes, a change made by the EuroLeague in 2006. The cost of equipment also creates a disparity, ensuring video review is only available at the professional or top-class level of play, not in amateur or grassroots sports where officials must rely solely on their live view.

Questions about Instant replay

Which Canadian sports leagues use instant replay for officiating?

Two major Canadian professional sports leagues use instant replay systems to assist officials. The National Hockey League (NHL) uses it to review goals and certain other calls. The Canadian Football League (CFL) also employs instant replay review for a variety of plays, including scoring plays and turnovers, similar to its use in the National Football League. The system is often managed by an instant replay official who can consult video footage before making or revising a decision.

How does instant replay work in basketball?

In the NBA, instant replay is used for several specific situations. It is mandatory to review shots at the end of a period to see if they were released in time, aided by LED lights on the backboard. Replay is also used to determine if a field goal is worth two or three points, to assess flagrant fouls and player ejections, to review block/charge calls, and to correct clock errors. Since 2014, the NBA has used a centralized replay centre in Secaucus, New Jersey, to support officials in all games. The system was first introduced in the 2002-03 season following a controversial playoff shot.

What technology is used for ball tracking in cricket replays?

Cricket's Decision Review System (DRS) uses several technologies. Hawk-Eye provides ball-tracking to show where the ball pitched and its point of impact on the batsman's leg, but it is not used to predict the ball's future path or height for LBW decisions under current protocols. Other tools include Snickometer, which analyses audio from stump microphones to detect edges, and Hot Spot, which uses thermal imaging to show where the ball has made contact. The TV umpire can use regular slow-motion, super-slow replays, and the replay mat.

Who are the leading manufacturers of instant replay equipment?

The dominant manufacturer of professional instant replay servers is EVS Broadcast Equipment, based in Belgium. Its systems are used in the majority of high-definition mobile production trucks and for major global events like the Olympics and Super Bowl. A 2019 survey found 213 of 257 HD trucks used EVS gear. Evertz Microsystems, a Canadian company, is another key player with its DreamCatcher replay system, widely used by professional sports teams in the NBA, MLB, and NHL for their in-venue and broadcast productions.

When was instant replay first used?

The first known use of a replay in a television broadcast was a wet film kinescope replay during a 1955 Hockey Night in Canada game on CBC Television. The first electronic instant replay system was invented by CBS Sports Director Tony Verna and deployed on December 7, 1963, for the Army Navy football game. The first known use of slow motion replay occurred on March 24, 1962, to review the end of a boxing match between Benny Paret and Emile Griffith several minutes after the bout ended. Verna's initial system used audio tones to mark exciting events for technicians to find during rewinding. This invention marked a post convergent moment for television, transforming how audiences viewed sports.

What is the Video Assistant Referee (VAR) in soccer?

The Video Assistant Referee, or VAR, is a system in association football where off field officials consult instant replay footage to assist the on field referee in making or revising decisions. It is used to adjudicate specific unclear or dubious plays during a match. FIFA did not formally permit video evidence to influence live match decisions until the 2018 FIFA World Cup, though it was used earlier for disciplinary sanctions. The system's adoption followed years of debate, with some officials arguing refereeing mistakes were part of the game's human element. Due to equipment costs, such video replay systems are typically only employed at professional or top class levels of play.

Sources and further reading

• Instant replay (Wikipedia)
• Look Again (canadashistory.ca)

Checked by the Your Space Hamilton desk. Last updated 2026-10-31.