The technical rules of swimming are designed to provide fair and equitable conditions of competition and to promote uniformity in the sport. Each swimming stroke has specific rules designed to ensure that no swimmer gets an unfair competitive advantage over another swimmer.

Trained officials observe the swimmers during each event to ensure compliance with these technical rules. If a swimmer commits an infraction of the rules that is observed by an offical, a disqualification (DQ) will result. This means that the swimmer will not receive an official time and will not be eligible for an award in that event. A disqualification may result from actions such as not getting to the starting blocks on time, false starting, performing strokes in an illegal manner, or unsportsman­like conduct. 

DQs are also a result of technical rules violations. They include but are not limited to: 

Freestyle: Walking on the bottom, pulling on the lane rope, not touching the wall on a turn, or not completing the distance.

Backstroke: Pulling or kicking into the wall once a swimmer has turned passed the vertical onto the breast. Turning onto the breast before touching the wall with the hand at the finish of the race.

Breaststroke: An illegal kick such as flutter (freestyle), dolphin (butterfly), or scissors (side stroke); not on the breast; alternating movements of the arms; taking two arm strokes or two leg kicks while the head is under water; touching with only one hand at the turns or finish. 

Butterfly: Alternating movements of the arms or legs; pushing the arms forward under instead of over the water surface (underwater recovery); a breaststroke style of kick; touching with only one hand at the turns or finish.

For specific language on any technical rules consult the USA Swimming Rules and Regulations book. Violations of the rules are reported to the Referee. The rules require that every reasonable effort be made to notify the swimmer or his coach of the reason for the disqualification. If your child is disqualified in an event, be supportive rather than critical. For beginning swimmers, a disqualification should be treated as a learning experience, not as a punishment. A disqualification alerts the swimmer and coach to what portions of the swimmer's stroke need to be corrected. They should be considered in the same light as an incorrect answer in schoolwork-they point out areas that need further practice. Disqualifications are necessary to keep the competition fair and equitable for all competitors. A supportive attitude on the part of the official, coach, and parent can make a positive situation out of the disqualification.

CMSL follows USS Rules in most cases.  Here is the link to: USA Swimming Rules and Regulations Books