It was controversial among people involved in correctional institutions as to whether Naikan was an act of religion, but the National Assembly of Governors of Prisons hosted by the Ministry of Justice in 1960 concluded that Naikan was not a religious act.
矯正界では内観が宗教に当たるのか当たらないのかで議論があったが、昭和35年の法務省主催の全国刑務所所長会同で「内観は宗教に当たらない」という結論が出された。