Instant replay in baseball
In Major League Baseball, a system similar to that in the National Hockey League for the last month of the 2008 season and beyond was implemented on August 28, 2008. The system allows instant replay to be used to review boundary home run calls to determine:
- fair (home run) or foul
- whether the ball actually left the playing field
- whether the ball was subject to spectator interference
A technician and an official (either an umpire supervisor or former umpire) monitor all games occurring at any given time from MLB.com's office in New York City (similar to the NHL system). Though a player or coach may argue for a review, final determination of whether a review will occur lies solely with the umpire crew chief, usually after consultation with the rest of the umpiring crew. If a crew chief believes a replay is warranted, he will go to a special console installed at every ballpark – accompanied by one or more members of the umpiring crew – and call the technician using the phone attached to the console. The technician in turn will feed the appropriate footage to the television screen. Upon reviewing the footage, the umpire must see "clear and convincing evidence" that the call on the field was incorrect in order to reverse it. Additionally, in the case of a home run call that is reversed (e.g., to a double), the crew chief is responsible for the placement of baserunners where they should have ended up had the correct call been made.
Instant Replay in MLB actually had been used once before in the 1999 season during a Florida Marlins home game at Pro Player Stadium. This was the first instance in which instant replay was utilized in Major League Baseball. While playing the St. Louis Cardinals, Cliff Floyd hit a ball off of the top of the left field scoreboard. Originally ruled a double, then ruled a home run, NL Umpire Frank Pulli reverted the call back to a double, after consulting a TV monitor in the Marlins dugout. The Cardinals won the game, 5-2, and the Marlins protested the use of the TV monitor. The National League Office declared the umpires erred in using Instant Replay, and the American League Office concurred that Instant Replay was not to be used in the future. However, the Marlins protest was denied on the grounds that it was a judgment call rather than a rules violation as such, and the play stood. MLB would not use Instant Replay again for almost a decade.
Although not an exact "instant" replay, a controversial play in the 1969 World Series involving a J. C. Martin bunt attempt led Commissioner Bowie Kuhn to study the videotape the next day, to assure himself and to announce that a reasonable call had been made by the umpires.
Major League Baseball instant replay was instituted on August 28, 2008 by commissioner Bud Selig. "I believe that the extraordinary technology that we now have merits the use of instant replay on a very limited basis", Commissioner Selig said. "The system we have in place will ensure that the proper call is made on home run balls and will not cause a significant delay to the game."
Although MLB was the last of the four major United States professional sports leagues to implement an instant replay review system, replay has been used 123 times between August 28, 2008 and the conclusion of the 2010 season (with 48 of those instances resulting in overturned calls).
Replay made its official, sanctioned MLB debut at Tropicana Field on September 3, 2008 after Alex Rodriguez of the New York Yankees hit a ball near the left-field foul pole that was initially ruled a home run by third base umpire Bryce DePuy. Tampa Bay Rays manager Joe Maddon and catcher Dioner Navarro argued that the ball was foul and asked for a review. After a conversation among the umpires, crew chief Charlie Reliford allowed the replay, which was sent by MLB.com logger Dominic Sims, to take place and after review, upheld the home run call.
The first instance of an umpire's call being overturned by instant replay also occurred at Tropicana Field. On September 19, 2008, in the bottom of the 4th inning with two men on, Carlos Peña of the Rays hit the ball just over the fence in right field. The umpires originally ruled that there was spectator interference, but after several minutes of viewing replays, the umpires returned to the field and signaled it a home run, extending the Rays' lead to 9-0 at that point.
Aside from the two aforementioned reviews at Tampa Bay, review was used five additional times during the 2008 regular season: Twice at Houston, and once each at Seattle, San Francisco, and Philadelphia.
World Baseball Classic 
On March 16, 2009, during the 2009 World Baseball Classic, instant replay was requested for the first time in the tournament's history at LandShark Stadium to give Venezuela a home run against Puerto Rico. Crew chief Ed Rapuano stated in a postgame press conference that there was never any replay, because the "war room" in New York City was unable to send him a replay of the play in question due to technical difficulties. The umpires, two from the United States and two from Japan, then worked with a translator to make a final ruling. Three of the four umpires said they believed it was a home run, and when third-base umpire Hitoshi Watarida was asked by Rapuano if he was "110 percent sure" that it was a home run, Watarida said yes. Nearly 10 minutes after first entering the dugout, the umpires returned to the field and awarded the Venezuelan team with a home run.
MLB Season and Post-Season 
On June 19, instant replay was used twice in a game for the first time, during the Detroit Tigers vs the Milwaukee Brewers game. This was also the first usage of instant replay in interleague history.
On October 31, 2009, instant replay was used for the first time in a World Series, when in the fourth inning of Game 3 of the World Series, Alex Rodriguez hit a ball that bounced off the camera in right field. Initially played as a double, the umpires reviewed the play, and determined that had the camera not been in its location, the ball probably would have left the park, and a home run was awarded to Rodriguez, making the score 3-2.
On June 1, 2011, Billy Butler of the Kansas City Royals hit a fly ball to left field in the bottom of the ninth inning of a scoreless game against the Los Angeles Angels of Anaheim. The ball hit off the fence over the left-field wall and skipped back onto the field. It was ruled a double and Jeff Francoeur held at third. Manager Ned Yost argued that it was a home run. The umpires reviewed it and saw that the ball hit off the back part of the fence and went back onto the field (in Kauffman Stadium, if the ball hits the back part of the fence, it is ruled a home run). The umpires ruled it a home run,winning the game for the Royals 2-0. This is the second walk-off home run reviewed by instant replay in MLB history.
On June 29, 2011, Jorge Posada of the New York Yankees hit a fly ball to right field. The ball bounced off the wall and a fan reached over to grab it. Originally ruled a base hit, instant replay showed that the fan touched the ball as it bounced back onto the field. After the review, the umpires called it a home run.
On August 17, 2011, Billy Butler hit a fly ball to left field. It hit off the railing in left. Brett Gardner grabbed the ball when it came back in and threw it into the infield. The umpires called it a home run. Joe Girardi came out to argue. The umpires looked at the review. The replays showed that the ball hit off the wall in left then came back out, so it would have been called a double, but the call stood, giving Butler his 15th home run of the season. Girardi and Mariano Rivera argued the call, but there were no ejections.
On August 18, 2011, Justin Morneau hit a deep fly ball to right field that appeared to go just to the right side of the foul pole for a foul ball. However, the umpires immediately called it a home run. For the second straight night, Joe Girardi came out to argue the call and ask for a review. The umpires reviewed and ruled that the ball did indeed go past the right side of the foul pole, thus calling it a foul ball. Twins manager Ron Gardenhire came out to argue the call and was ejected from the ballgame for arguing a decision to change a call after looking at instant replay, which usually results in an automatic ejection.
On September 4, 2011, Hunter Pence of the Philadelphia Phillies hit a fly ball to deep right field. Originally ruled a live ball, instant replay showed Marlins right fielder Bryan Petersen was interfered with by multiple fans during his opportunity to catch a ball, under Rule 2.00 INTERFERENCE (d)(1) and (2). After instant replay review, first base umpire and crew chief Joe West ruled Pence out under the provisions of spectator interference, Rule 3.16, and sent Phillies baserunner Ryan Howard back to first base. For the second time in less than a month, a manager was ejected arguing the instant replay decision: Charlie Manuel was ejected and elected to play the game under protest. On September 7, 2011, MLB VP of Baseball Operations Joe Torre denied the first ever protest associated with authorized instant replay usage.
During the 2011 American League Division Series, Robinson Canó of the New York Yankees hit a fly ball to left field. It bounced off the wall and back into play. Cano argued that the ball went over the wall. Instant replay showed that the ball bounced off the wall and narrowly missed a fan, bouncing back into play. Therefore, the call stood.
Changes pending for 2014 
As part of the new collective bargaining agreement between MLB's owners and players union, and pending approval by the umpires union, two additional elements will be added to the replay rules. Instant Replay will expand to include fair and foul calls and balls that are caught, or trapped by the player catching the ball. It will also expand interference reviews beyond the home run boundary to all walls. Not expanded in 2012, Executive Vice President of Baseball Operations Joe Torre confirmed that instant replay would again not be expanded in time for Opening Day 2013, putting off plans for yet another season. 
MLB's use of instant replay has already begun to spark controversy. Some fans are upset with the fact that the MLB system solely works in accordance with home run calls and no other part of the game. Such fans may believe the MLB needs to incorporate replay reviews in other areas of the game where missed calls frequently arise, such as:
- Baserunning (whether a player is safe or out on the bag)
- Plate Calling (whether a player is out or not on a bad call by the umpire behind home plate)
- Non-Fair Fly Ball Spectator Interference (whether a player should be out or safe on foul balls)
- Whether or not a batter is hit by a pitch
Umpire Jim Joyce's incorrect safe call at first base on June 2, 2010 which deprived Detroit Tigers pitcher Armando Galarraga of a perfect game has led to calls for using instant replay beyond deciding home runs.
- Curry, Jack (August 27, 2008). "Baseball to Use Replay Review on Homers". New York Times. Retrieved 2008-10-01.
- "GMs vote 25-5 to use replay to aid home run decisions". ESPN.com. November 6, 2007.
- "Sharp Offers Baseball-Themed Promotions During MLB Postseason" (Press release). CEPro. October 8, 2008.
- "Marlins object to umps watching TV". CNN. June 1, 1999.
- "Marlins' 'Replay' Protest Denied". Los Angeles Times. June 4, 1999.
- "NL president: Umpire erred in consulting replay". CNN. June 2, 1999.
- "Instant Replay at a Glance". October 20, 2010.
- Instant replay goes off without a hitch
- Umpires don't use replay in Classic
- "Instant Replay Debuts at World Baseball Classic", Close Call Sports, March 8, 2013
- MLB.com 6/19/09 Tigers rain down runs on Brewers
- "Ejections: Joe West (7)". Retrieved 4 September 2011.
- "Expanded Replay Not on Par for Opening Day 2013", Close Call Sports/Umpire Ejection Fantasy League, February 19, 2013