Horse - collar tackle The horse - collar tackle is an American football maneuver in which a defender tackles another player by grabbing the back - inside of an opponent ' s shoulder pads . The technique is most closely associated with Pro Bowl safety Roy Williams . This kind of tackle was banned from the NFL during the 2005 offseason . The rule forbidding it is often referred to in the press as " The Roy Williams Rule " . The rule , with modifications , was adopted in college football in 2008 and high school football in 2009 . History . The horse - collar tackle rose to infamy during the 2004 NFL season , in which it was implicated for six major injuries , four of which were caused by Williams , including two in one game . The injuries that season included broken legs for Philadelphia Eagles wide receiver Terrell Owens , Eagles quarterback Donovan McNabb , Baltimore Ravens running back Musa Smith , and Tennessee Titans wide out Tyrone Calico . On May 23 , 2005 , NFL owners voted 27 – 5 to ban the tackle , with the Dallas Cowboys , Detroit Lions , New England Patriots , New Orleans Saints , and San Francisco 49ers voting against . The first year of the ban , only two penalties were called by referees for the horse - collar tackle . Owners voted 25 – 7 in 2006 to expand the rule to include tackles by the back of the jersey in addition to tackles by the shoulder pads . Risks . The horse - collar is particularly dangerous due to the awkward position of the player being tackled , who will often fall backward in a twisting motion with one or both legs trapped under the weight of his body . This is exacerbated if the player ' s foot gets caught in the turf and by the additional weight of the defender . Potential injuries include sprain s or tears to ligaments in the knees and ankles ( including the ACL and MCL ) , and fractures of the tibia and fibula . The ban states that a horse - collar tackle is an open - field tackle in which a defender uses the shoulder pads or jersey to immediately bring a ball carrier down . The term " open field " means that horse - collar tackles committed near the line of scrimmage will be allowed ; in addition , the stipulation of " immediately bringing the ball carrier down " means that , if a defender begins to bring a player down by the shoulder pads but lets go before the tackle is completed , he will not be penalized . Punishment . In the NFL , the horse - collar tackle results in a 15 - yard personal foul penalty and an automatic first down if committed by the defense ( penalty also will be enforced even if the opposing offense gains yards ) . It will often also result in a league - imposed fine on the player . Roy Williams was the first player suspended for repeated violations of the rule . The one - game suspension was given following a horse - collar tackle on Philadelphia Eagles quarterback Donovan McNabb that occurred on December 16 , 2007 , and it was Williams ' third violation of the rule of the 2007 season . The tackle was made illegal in the CFL for the 2007 season . The horse collar tackle was legal through the 2007 – 2008 season in college football but was banned by the NCAA after criticism from pundits and coaches for the 2008 – 2009 season as part of a package that adopted several NFL rules into the college game . The National Federation of State High School Associations added a penalty for horse - collar tackles for the 2009 season .