While Chief Justice Roberts’ “calling balls and strikes” analogy is  overly simplistic and inaccurate, sports rules do, in fact, illustrate a great deal about legal rules and legal decisionmaking. A new example came last week, when Major League Baseball announced an experimental rule banning, or at least limiting, home-plate collisions. The rule is intended to protect players, especially catchers;  home-plate collisions are a common cause of concussions and other injuries. Whether the rule does or not achieve that goal offers an interesting exercise in statutory interpretation and thus in how rules are made and enforced.

New Rule 7.13 of the Official Baseball Rules provides:

A runner attempting to score may not deviate from his direct pathway to the plate in order to initiate contact with the catcher (or other player covering home plate). If, in the judgment of the umpire, a runner attempting to score initiates contact with the catcher (or other player covering home plate) in such a manner, the umpire shall declare the runner out (even if the player covering home plate loses possession of the ball). In such circumstances, the umpire shall call the ball dead, and all other baserunners shall return to the last base touched at the time of the collision.

An interpretive comment adds:

The failure by the runner to make an effort to touch the plate, the runner’s lowering of the shoulder, or the runner’s pushing through with his hands, elbows or arms, would support a determination that the runner deviated from the pathway in order to initiate contact with the catcher in violation of Rule 7.13. If the runner slides into the plate in an appropriate manner, he shall not be adjudged to have violated Rule 7.13. A slide shall be deemed appropriate, in the case of a feet first slide, if the runner’s buttocks and legs should hit the ground before contact with the catcher. In the case of a head first slide, a runner shall be deemed to have slid appropriately if his body should hit the ground before contact with the catcher. Unless the catcher is in possession of the ball, the catcher cannot block the pathway of the runner as he is attempting to score. If, in the judgment of the umpire, the catcher without possession of the ball blocks the pathway of the runner, the umpire shall call or signal the runner safe. Notwithstanding the above, it shall not be considered a violation of this Rule 7.13 if the catcher blocks the pathway of the runner in order to field a throw, and the umpire determines that the catcher could not have fielded the ball without blocking the pathway of the runner and that contact with the runner was unavoidable.

The rule reportedly reflects a compromise between Major League Baseball, which had wanted a must-slide-can’t-block rule that would have eliminated all home-plate collisions and thus done the most for player safety, and the MLBPA, which did not want to make such a major change so close to the season, fearing the players would not have time to adjust.

The basic rule prohibits a runner from deviating from the direct path home to initiate contact with the catcher (or whoever is covering the plate)–that is, from going out of his way to make contact, rather than running in the straightest line for home plate. But the rule does not prohibit collisions where the runner runs directly into the catcher in trying to score. Reading only the text, it is not clear that the new rule eliminates most collisions, since most collisions come when runner, catcher, and ball all converge at the plate and running through the catcher is the most direct route to scoring. It thus is not clear that it provides the safety benefits it is intended to provide.

The solution may come in the interpretive comments and a more purposivist approach to the interpretation and application of the rule.

An umpire may find that the runner deviated if the runner fails to make an effort to touch the plate, lowers his shoulder, or pushes with his hands, elbows, or arms. On the other hand, a runner does not violate the rule if he slides into the plate in an “appropriate manner,” meaning body hits the ground before making contact with the catcher (the lower body on a feet-first slide, upper body on a head-first slide). The upshot is that umpires wield discretion to judge when the runner has “deviated” from the path, and thereby to apply the rule so as to further its purpose. That incentivizes runners to slide in most cases; a proper slide per se will not violate the rule, while running through the catcher might be deemed deviating, subject to how the umpire views the play (whether the runner lowered his shoulder or raiseed his arms, etc.).

The statutory purpose is furthered by the second interpretive comment, under which catchers may not block a runner’s pathway to the plate if the catcher is not either in possession of the ball or attempting to field a throw. This comment mirrors the basic definition and interpretation of “obstruction” elsewhere in the baseball’s rules–a fielder cannot impede a runner’s progress, unless in possession of the ball or in the act of fielding a ball, including trying to catch a thrown ball. Again, the new incentive is for catchers to move away from the plate on most plays, leaving the runners more room to run or slide directly into the plate, and avoiding most collisions.

The ultimate goal of the new rule is to make plays at the plate look more like plays at the other three bases–runners slide, fielders cannot block the path to a base unless holding the ball or trying to catch it. Perhaps it would have been clearer and less complicated had the text been more explicit in imposing that as a requirement, rather than relying on supporting comments to incentivize the preferred actions. But the prevailing view is that this rule is experimental, designed to be revisited during and after the upcoming season; it functions as a first step to get players used to this new way of playing at the plate.

Think of it as the legislature phasing-in new rules so as to also phase-in new, preferred behavior. And another example of the rules of sport telling us about the rule of law.