[smithma]

7.08 -- Any runner is out when -
(a) (1) running more than three feet away from his/her baseline to avoid being tagged, unless such action is to avoid interference with a fielder fielding a batted ball. A runner’s baseline is established when the tag attempt occurs and is a straight line from the runner to the base which he/she is attempting to reach; or
(2) after touching first base the runner leaves the baseline, obviously abandoning all effort to touch the next base; or
(3) the runner does not slide or attempt to get around a fielder who has the ball and is waiting to make the tag; or
(4) the runner slides head first while advancing.

INSTRUCTOR COMMENTS: This rule does not apply when a runner is returning to a base, only when advancing to a base. Any runner who does a headfirst slide is out at the moment the umpire sees the runner go into the headfirst slide. The ball remains alive and in play and runners may advance at their own risk and plays may be attempted on any other runners. If the runner who is called out for sliding headfirst has been forced to advance by the batter-runner this will be a force out and no runs will score if this is the third out of the inning. In all other instances the headfirst slide will be a timing play when there are two outs.