This is also one of the most significant weaknesses of benchmarking in legal services: so many factors directly responsible for the success or failure of case outcomes is beyond the ability of the firm to overcome through a positive result. On the other hand, it also gives rise to one of the most significant measures of organizational success. Since clients whose cases can be resolved in their favor or to their satisfaction are naturally inclined to continue their association with the firm, a substantial part of law firm success is a measure of the organization's ability to retain clients whose desired objectives the firm was incapable of achieving.

Application to U.S. Air Force Foreign Legal Services Offices

Whereas legal services performed on behalf of active service members by the U.S. Air Force are virtually identical to those services rendered to clients by civilian...

Specifically, it is very difficult to measure client satisfaction in terms of retention because active service members receive their legal services without cost; any alternative would necessarily be at considerable financial cost. Similar differences apply to other standard measures of benchmarking such as staff retention and promotions. Nevertheless, in principle, benchmarking can be a valuable mechanism for armed forces legal services provided the specific surveys and other information collection tools are appropriately designed to provide the same type of information that ordinarily correspond to best practices in the legal profession.
Reference

Russell-Whalling E. (2008). 50 Management Ideas You Really Need to Know. London:

Quercus