Validity of regression therapy and degree of acceptance of the subject within the psychology community I had a debate with my friend on regression therapy as he feels it is an accepted method to discover a person's past life &amp; his memories. I find it completely unacceptable to my sense. 

What studies have been done regarding the effectiveness of regression therapy and to what degree is this practice accepted by mainstream clinicians?

I can agree regression therapy on to get to forgotten, ignored or repressed experiences that are bothering people and helping them to overcome their problems which similar to memory therapy. But I cannot understand the logic of extracting past life experiences and past life memory. It is totally indigestible that psychologists (specially in India) believe in these practices.  Or is that a few of psychologists are misusing the profession for monetary gains.
There is an article on Wikipedia discussing past life regression.

A general scientific explanation of beliefs about past lives is that:


  the memories are the result of
  cryptomnesia, narratives created by the subconscious mind using
  imagination, forgotten information and suggestions from the
  therapist.[1][2][3][15][16][17][18] Memories created under hypnosis
  are indistinguishable from actual memories and can be more vivid than
  factual memories.[2][19] The greatest predictor of individuals
  reporting memories of past lives appears to be their beliefs about the
  existence in reincarnation - individuals who believe in reincarnation
  are more likely to report such memories, while sceptics or
  disbelievers are less so.[1][5]


The study discussed in Spanos (1996) sounds particularly relevant to understanding the nature of such past life beliefs. To continue quoting the Wikpedia article:


  Spanos' research leads him to the conclusion that past lives are not
  memories, but actually social constructions based on patients acting
  "as if" they were someone else, but with significant flaws that would
  not be expected of actual memories. To create these memories, Spanos'
  subjects drew upon the expectations established by authority figures
  and information outside of the experiment such as television, novels,
  life experiences and their own desires.


Thus, past life regression therapy is invalid in the sense that patients are not actually recalling past lives.  Nonetheless, there still remains a question of whether it offers therapeutic benefits. Meaning,  purpose, and self-esteem are all important human needs. For therapists and patients who believe in past lives,  fleshing out past lives could potentially help to fulfil such needs. That said, I don't know of any scientific studies that have evaluated such therapy. Such therapy also raises a number of ethical issues in terms of fostering illusions in the client. 

References


Spanos NP (1996). Multiple Identities &amp; False Memories: A Sociocognitive Perspective. American Psychological Association (APA). pp. 135–40. ISBN 1-55798-340-2.