The Three Seconds Good Defense Rule (also called Three Seconds Closely Guarded) is an offensive foul only applicable to the non-check youth girls game. The rule can be confusing because it occurs during active play without evidence of any physical violation. It is tucked in the carve out for youth rules in the US Lacrosse Womens Rule Book in the Fouls section.
Here’s an example of the foul. An offensive player possessing the ball is racing up the sideline with the ball perched in her pocket and holding the stick in a slightly horizontal fashion – like a 3rd grader does. A defender is pursing alongside. Mom thinks her girl has a chance for a goal and has jumped from her chair to cheer and then there is a whistle. The referee stops play and awards the ball to the defender. The sideline murmurs “what?”.
Here is the rule as written in the rule book:
9. Player with the ball may not hold the ball for more than 3 seconds when
a. closely guarded/marked (see definitions)
b. the defender has both hands on her stick
c. the defender is in position to legally check if checking was allowed. (U-13 and below; U-15 if criteria is not met). (Minor Foul)
So if a defender (or more than one) is closely guarding a ball carrier, has two hands on her stick and has the opportunity to safely check the ball away – if it were allowed – and maintains that position over a three second count she (the defender) will be awarded the ball for good defense.
As far as the intention; the rule has two parts. It gives the defense an advantage or opportunity to gain possession when they are restricted by rule of being physically able to dislodge the ball (stick check). It requires the offensive player to practice good cradling technique, which will develop better stick protection skills needed for the checking game.
To avoid the foul, the offensive player needs to change direction, change her cradle, switch hands, or otherwise make some adjustment with the ball in her pocket so that a safe check – if it were allowed – could no longer be made. Once the ball carrier makes an adjustment the count is over, but could be resumed again if the conditions described above return. The new count will begin again from 1 and not where the initial count ended.