Rupture of the anterior cruciate ligament (ACL) results in increased tibiofemoral laxity in the knee, thereby ultimately resulting in knee instability and dysfunction. However, ACL rupture does not automatically infer functional impairment and instability as confirmed by the ACL deficient (ACLD) coper, who can resume pre-morbid activity levels. Alternatively, an authentic ACLD non-coper is unable to return to pre-injury levels of activity due to repeated incidents of giving-way. Little is known as to the contributory factors, which allows copers dynamic stability and render non-copers functionally impaired. This systematic literature review aims to examine the evidence presented by relevant trials in order to identify measurement tools, which could differentiate ACLD copers and non-copers. A literature search found nine trials; four adhered to the inclusion criteria of this review. Consensus was achieved within the studies that laxity measurements and IKDC ratings are incapable of distinguishing the functional status of the ACLD patient. Alternatively, Lysholm, KOS-Sport, KOS-ADL and Global Knee Function Rating Scores were regarded as capable of discriminating between ACLD copers and non-copers. Disagreement existed as to the efficacy of the Quadriceps Index and the single leg hop in categorising the ACLD patient according to function level. It was concluded that no single measurement tool is sufficient in determining the functional status of the ACLD individual. Consequently, a collaboration of tests is recommended, specifically incorporating the KOS-Sport, Global Knee Function Rating, hop tests and Quadriceps Index.