Braye and Preston-Shoot (2007) point out some limitations of a "Gold Standard" or Hierarchy of Evidence" worth remembering for social workers:

• "'Evidence-based policy and practice' ...conceals complex debates about the nature of research and role of evidence" in social work, law, education, and other non-medical helping professions (p. 314).
  
• "[T]here is recognition that the sources of social care knowledge are diverse, with organizations, policy makers, professionals, and users making equally valuable contributions, alongside research." (p.315)
  
• "[T]here are limitations to a model that favours solely experimental research, which can only answer a limited range of questions and is not always sensitive to broad questions of values and ethics'" (p. 316).
  

Source: Braye, S. and Preston-Shoot, M. 2007. On systematic reviews in Social Work: Observations from teaching, learning and assessment of law in social work education. British Journal of Social Work, 37, 313-334.

Westin, Novotny, and Thompson-Brenner (2004) also provide a critical review of the "gold standard" of controlled clinical trails in regard to psychotherapies.

Source:: Westin, D., Novotny, C. M., and Thompson-Brenner, H. (2004). The empirical status of empirically supported psychotherapies: Assumptions, findings, and reporting in controlled clinical trials. Psychological Bulletin, 130(4), 631-663. http://imagesrvr.epnet.com/embimages/pdh2/bul/bul1304631.pdf

Further,

• Clinical trails are in controlled settings
• Supervision by developers of the model stand by to ensure high treatment fidelity
• Not possible to have this level of control in community settings
• Need to build partnerships between clinical practitioners and researchers to maintain the fidelity and effectiveness of the intervention

[Source: Franklin, C. and Hopson, L.M. (2007). Facilitating the use of evidence-based practice in community organizations. Journal of Social Work Education, 43(3), 377-404.