2007 USMS Rule Book, Article 101.2: BREASTSTROKE
101.2.1 -- Start
The forward start shall be used.
101.2.2 -- Stroke
From the beginning of the first arm stroke after the start and after each turn, the body shall be kept on the breast. The arms shall move simultaneously and in the same horizontal plane without any alternating movement. The hands shall be pushed forward together from the breast on, under, or over the water. The elbows shall be under the water except for the final stroke before the turn, during the turn, and the last stroke at the finish of the prescribed distance. The hands shall not be brought back on or under the surface of the water. The hands shall not be brought beyond the hip line, except during the first stroke after the start and each turn. Some part of the swimmer's head shall break the surface of the water at least once during each complete cycle of one arm stroke and on leg kick, in that order, except after the start and each turn the swimmer may take one arm stroke completely back to the legs and one leg kick while wholly submerged. The head must break the surface of the water before the hands turn inward at the widest part of the second stroke.
101.2.3 -- Kick
All vertical and lateral movements of the legs shall be simultaneous. The feet must be turned outward during the propulsive part of the kick movement. A scissors, flutter, or downward butterfly kick is not permitted. Breaking the surface with the feet shall not merit disqualification unless followed by a downward butterfly kick.
101.2.4 -- Turns
At each turn, the touch shall be made with both hands simultaneously at, above, or below the water surface. The head may be submerged after the last arm pull prior to the touch, provided it breaks the surface of the water at some point during any part of the last complete or incomplete stroke cycle preceding the touch. Once a touch has been made, the swimmer may turn in any manner desired. The shoulders must be at or past the vertical toward the breast when the swimmer leaves the wall and the form prescribed in article 101.2.2 must be attained from the beginning of the first arm stroke.
101.2.5 -- Finish
At the finish, the body shall be on the breast and the touch shall be made with both hands simultaneously at, above, or below the surface of the water. The head may be submerged after the last arm pull prior to the touch, provided it breaks the surface of the water at some point during any part of the last complete or incomplete cycle preceding the touch.