A: There is nothing in the soccer laws specifically permit or prohibit ST. Referees have to make their decisions on the basis of whether an action constitutes a foul (e.g., "tripping") or "dangerous play". Play that trips another person without having any effect on the ball's movement is not legal. Every referee's definition of what is safe (or dangerous) play is different. Some referees blow the whistle whenever somebody falls down. Other referees use the "all ball" guideline: A ST is fair if it redirects the ball out of the dribble path even if the opponent trips over some part of your horizontal leg afterwards.

Slide tackling is not a skill that you "just do." SAYSO players learn proper ST technique that results in safe play for both teams.