A system and method of knee-ACL support breeches for supporting the knees against non-contact anterior cruciate ligament (ACL) injuries, without interfering in desired movement, by resisting anterior translation of the proximal end of the tibia, thereby reducing stress on the ACL and other knee components. A pair of calibrated-elastic bands are attached at one end to a belt about the waist and at the other end to a strap around each lower knee. The calibrated-elastic bands are incorporated into a pair of breeches or pants which hold the bands tightly against the buttocks and backs of the thighs. In use, when the knee is flexed, the resulting bulging of the hamstrings and other muscles, tendons, and ligaments place an added strain on the relevant calibrated-elastic band, thereby tightening the band and dampening and resisting anterior movement of the attached lower-knee strap, in turn dampening and resisting anterior movement of the proximal end of the tibia, thereby reducing strain on the ACL and other knee components. The knee-ACL support breeches also promote the holding of the knee in a rotationally neutral position, and larger knee-flexion-angle positions during deceleration, both of which positions reduce strain placed on the ACL.