Is mutually consensual BDSM a symptom of a sick mind or an expression of freedom from social constraints? BDSM an acronym for bondage and discipline; dominant and submissive; sado-masochism; slave and master. 

Assume such a relationships or sexual practices are genuinely mutually consenting; and by consent I mean, meaning two well informed, mature, sober, drug free adults.
In such cases, are BDSM practices or relationships a symptom of a sick mind or the true freedom from social conditioning to play and experiment as desired?

When answering one must be mindful to put the moral judgment that away.
Answers based purely on opinion and without references will be down voted and flagged, as it is not a site for moral argument, but built on latest scientific research.
If your question is, whether practitioners of BDSM are in some way pathological, then Pamela Connolly (2006) answered it. Her abstract summarizes her research and findings nicely (emphasis added):


  A demographic questionnaire and 7 psychometric tests were administered
  to 32 self-identified Bondage/Domination/SadoMasochism (BDSM)
  practitioners. Although psychoanalytic literature suggests that high
  levels of certain types of psychopathology should be prevalent among
  BDSM practitioners, this sample failed to produce widespread, high
  levels of psychopathology on psychometric measures of depression,
  anxiety, obsessive-compulsion, psychological sadism, psychological
  masochism, or PTSD. In fact, on measures of clinical psychopathology
  and severe personality pathology, this sample appeared to be
  comparable to both published test norms and to DSM-IV-TR estimates for
  the general population. There were, however, some exceptions to this
  general pattern, most notably the higher-than-average levels of
  narcissism and nonspecific dissociative symptoms found in the sample.
  This study also raises significant concern about the appropriateness
  of the diagnosis of sexual masochism and sadism in the Diagnostic and
  Statistical Manual of the American Psychiatric Association or,
  minimally, the diagnostic criteria of these disorders.


But BDSM practitioners aren't only normal, they feel "more better", too: An Australian study (Richters, De Visser, Rissel, Grulich, &amp; Smith, 2008) found that "men who had engaged in BDSM scored significantly lower on a scale of psychological distress than other men" (emphasis added).

This higher level of well-being may be explained by conscious and systematic "relationship management", including no-holds-barred open communication and clear agreement on mutual relationship roles, resulting in highly functional relationships, as well as a commitment to personal growth, both of which are common among BDSM couples (Cutler, 2003). Contrary to common views of BDSM, Cutler states, BDSM activities include non-sexual motivations: "hormonal studies have shown BDSM activities to be more similar to sports than sex, complete with stress relief qualities" (emphasis added).

Today, BDSM is a best-selling mainstream media phenomenon, and it has become increasingly difficult to draw a clear distinction between "deviant" and "normal" sexuality. When a little rope play is just another practice for the average couple, BDSM certainly isn't deviant any longer, and many practitioners are as "normal" as you and me. The difference in practice is, I believe, gradual: BDSM couples indulge in "normal" sex just as normal couples pay visits to the land of bondage and submission (and other kinks).




Connolly, P. H. (2006). Psychological Functioning of Bondage/Domination/Sado-Masochism (BDSM) Practitioners. Journal of Psychology &amp; Human Sexuality, 18, 79-120. doi:10.1300/J056v18n01_05
Cutler, B. (2003). Partner Selection, Power Dynamics, and Sexual Bargaining in Self-Defined BDSM Couples (Doctoral dissertation, Institute for Advanced Study of Human Sexuality). Retrieved from http://www.niu.edu/user/tj0bjs1/bdsm/Cutler%20(2003).pdf
Richters, J., De Visser, R. O., Rissel, C. E., Grulich, A. E., &amp; Smith, A. M. A.
(2008). Demographic and psychosocial features of participants in bondage and discipline, "sadomasochism" or dominance and submission (BDSM): Data from a National Survey. The Journal of Sexual Medicine, 5, 1660–1668. doi: 10.1111/j.1743-6109.2008.00795.x