Section 22(5) in The Bihar Juvenile Justice (Care and Protection of Children) Rules, 2003
(5)In every case concerning a juvenile or a child, the Board shall either obtain -(i)a birth certificate given by a Corporation or a Municipal Authority; or(ii)a date of birth certificate from the school first attended; or(iii)Matriculation or equivalent certificate, if available; and(iv)in the absence of (i) to (iii) above, the medical opinion by a duly constituted Medical Board, subject to a margin of one year, in deserving cases for the reasons to be recorded by such Medical Board, regarding his age; and, when passing orders in such case shall, after taking into consideration such evidence as may be available or the medical opinion, as the case may be, record a finding in respect of his age.
