The Research Doctorate  (doctor of  physiko-mat. nauk)  requires  writing a  thesis  based  on original research.  The  preliminary detailed evaluation of the research merit is conducted   by several officially appointed  experts in  the area of the thesis. The author and the referees orally present their views at a meeting of the specially appointed academic council of 10-20 experts. Academic council has the authority only to recommend the award of the research doctorate by the Higher Attestation Commission (VAK). According to the  Higher Attestation Commission  a research doctorate is  expected: 

… to reveal independent research and work resulting in a  solution or a theoretical generalization of scientific problems,  or a scientifically valid formulation of new problems which  represent considerable scientific interest. The High Attestation  Commission reviews  the  process  and approves or disapproves  the recommendation made by  the committee. In the  former Soviet  Union  slightly  over  10%  of  holders  of   Ph.D. attained  Research  Doctorate. Normally,   the   Research Doctorate  is required  in order to  get  a  position  of a Chief Research  Fellow  (a  Russian  equivalent  of  Full Professor in a research institution). For more details, see, A.G. Korol,  Soviet Education for Science and Technology, Greenwood Press, Publishers Westport, Connecticut