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The libero player in volleyball was introduced internationally in 1998. This defensive specialist can replace any back-row player without prior notice to the officials. The rule evolved to include limitations on the libero's actions, such as not being allowed to serve or spike the ball. This position was added to enhance the defensive aspect of the game and to add a tactical element.

In track cycling, the elimination race format, sometimes called 'Devil Take the Hindmost,' involves removing the last cyclist on every 2nd lap. This was introduced to create a more spectator-friendly and high-stakes environment within velodrome races.

The compound bow was officially introduced to archery competitions in the 1980s, offering an alternative to the recurve bow with its different mechanical advantages. This addition has diversified the sport and allowed for more variation in technique and equipment.

In 2010, the International Judo Federation banned leg grabs and tackles from standing positions. This controversial rule change aimed to distinguish judo more clearly from other grappling sports and to promote traditional judo techniques focused on throws.

Badminton shifted from a traditional 15-point scoring system to a 21-point rally scoring system in 2006. This was done to make matches shorter and more exciting, and to make it easier for television audiences to follow the sport.

The shot clock in basketball was introduced in 1954 to prevent teams from stalling. It originally gave teams 24 seconds to attempt a shot. Over time, different leagues have experimented with different durations, like the 30-second shot clock in women's NCAA. The main reason for these changes is to maintain a steady pace of play and to increase scoring opportunities.

The official diameter of table tennis balls increased from 38mm to 40mm in 2000. This change was made to slow down the game a bit and make the sport more viewer-friendly by making rallies last longer and the ball easier to see on television.

Electronic scoring vests were introduced into taekwondo to provide a more objective system for scoring hits. The technology continues to evolve to improve the accuracy of scoring and reduce human error, enhancing the fairness and credibility of the sport.

Helmet-to-helmet contact in American football was legal until the NFL began to implement rules against it in the 1970s, with more stringent regulations coming into place in the 2000s. This was done in response to medical research showing the long-term impact of concussions and other head injuries, to increase player safety.

The tie-break was introduced in tennis in the 1970s to resolve set ties without the games continuing indefinitely. The traditional 7-point tie-break is used when the score reaches 6-6 in games. Some tournaments now use a 10-point tie-break in the final set to shorten match lengths. This was implemented to reduce player fatigue and to make scheduling of matches more predictable.

The use of helmets in competitive skiing became mandatory across all disciplines post-2007 to improve safety and reduce the risk of head injuries. This followed several incidents in which injuries could have been lessened or prevented by the use of a helmet.

The judging system in figure skating moved from a 6.0 scale to the International Judging System (IJS) after the 2002 Winter Olympics judging scandal. The IJS employs a points-based system, aiming to reduce subjectivity and making scoring more transparent and fair.

Photo finish technology was introduced to rowing to resolve races with extremely close finishes. The technology has evolved with high-speed cameras to provide accurate placings, which is vital in a sport with finish differences often in the milliseconds.

The passivity rule, also known as 'non-combativity,' in fencing results in penalties for fencers who do not engage in combat for a period of time. This rule has been refined to encourage fencers to continuously engage with each other, making matches more dynamic and interesting for spectators.

The false start rule in swimming originally allowed each swimmer one false start before being disqualified. It was changed to an immediate disqualification upon a single false start to reduce delays and unfair advantages. This shift took place ahead of the 2009 World Championships.

Historically in golf, the penalty for a lost ball or a ball hit out of bounds was stroke and distance. Recent updates to the rules allow for a local rule letting players take a drop near where the ball was lost or went out of bounds, with a two-stroke penalty. This was changed to help improve pace of play and reduce frustration for recreational players.

In show jumping, a jump-off is used to break ties in which multiple riders have incurred the same number of penalty points. This rule has evolved to include timed jump-offs, adding an element of speed to the competition, thereby increasing its excitement and appeal.

The LBW law in cricket has been a part of the game since the 18th century but has undergone various refinements. Initially, the ball had to pitch in a straight line between wicket to wicket for an LBW appeal to be upheld. Now, where the ball pitches has expanded, and technology helps in determining if it would have hit the stumps. These changes aim to make the law less batsman-friendly and to balance the game between bat and ball.

The two-line pass rule in ice hockey, which prohibited players from passing the puck across two lines on the ice, was removed from the NHL in 2005. This rule change was part of an effort to speed up the game, promote offensive play, and reduce stoppages, especially after the 2004-2005 NHL lockout.

Formula 1's qualifying format has seen numerous changes, moving from the traditional two sessions of timed laps to the current three-part knockout system. The knockout format was adopted in 2006 to make qualifying more entertaining and competitive for both drivers and spectators.

The offside rule in soccer has seen various changes since its inception in the 19th century. Originally, a player was offside if they were ahead of the ball at the moment it was played. Over time, the rule evolved to allow a player to be onside as long as two opposing players (one of which is usually the goalkeeper) are between the player and the opposing goal when the ball is played. These changes were made to promote more attacking play and reduce stoppages.

Instant replay was introduced in Major League Baseball (MLB) in 2008, initially limited to boundary home run calls. In 2014, MLB expanded instant replay to allow for reviews of other on-field decisions. The change was motivated by the desire to improve accuracy of critical decisions and reduce controversy surrounding plays that might impact the outcome of the game.

In rugby, the point value for tries, conversions, penalties, and drop goals has changed over time to alter the strategic approach of the game. Tries have gone from no points with an opportunity for a conversion, to being worth up to 5 points, with the goal of encouraging more attacking play and making the game more exciting for spectators.