Must Slide Rule

Question
I've coached a fastpitch softball team for years (currently coaching U18 team) and have often heard umpires refer to the "must side" rule.  Every umpire has a different interpretation -- some say it exists, some say it doesn't exist, some say it's not in the ASA rules but they're told to enforce it nonetheless, etc.  In a game last night one of my players was called out at home because she didn't slide -- costing us the game.  The umpire stated that if there's a play at the plate (but not 1st, 2nd or 3rd) the runner must slide.  BTW, the runner reached the plate a half step before the ball.  I checked the ASA rulebook and can find nothing  under Rule 8 (Batters as Runners and Runners) regarding a "must slide" rule.  Can you please clarify whether or not there is a "must slide" rule?  Thank you.

Answer
Hi Brian,

there are no "must slide" rules from any major nat org that I know of and CERTAINLY ASA has NO must slide rule, it's not necessary. You might have a local rule to that effect but only your LD can tell you.  If you don't have one then protest the next time it happens.

In your particular play how can the catcher be put in physical jeopardy if they don't have the ball.  By rule they cannot block the base or basepath w/out possession of the ball.  I think it's a stretch to call that a play at the plate if the runner had already touched it at the time the catcher received the throw.

Mark