Judgment K.M.Natarajan. J: The detenu has filed this writ petition under Art.226 of the Constitution of India for the issuance of a writ of habeas corpus quashing the order of detention passed against him. 2. The impugned order was passed on 28th July, 1987 by the second respondent the District Magistrate and Collector of Chingleput District under S.3(1) of Tamil Nadu Prevention of Dangerous Activities of Bootleggers, Drug Offenders, Goondas, Immoral Traffic Offenders and Slum Grabbers Act, 1982 (Tamil Nadu Act 14 of 1982) (hereinafter referred to as ‘Act’) with a view to preventing him from acting in many prejudicial to the maintenance of public order. 3. The detenu came to the adverse notice, as bootleggers in the two earlier cases and in the instant case referred to in the grounds of detention and he was detained in the ground case. The learned counsel for the petitioner detenu Mr. S. Shanmugha Velayutham, challenged the order of detention on the only ground that admittedly the detenu was on bail on the date when the detention order was passed. In the foot of the grounds of detention as well as in the detention order, it is mentioned that the service to be effected through the Superintendent, Central Prison, Madras and it shows that the detaining authority was not aware whether the alleged detenu was on bail or not, and has passed the impugned order mechanically without applying his mind. Hence the order is vitiated. To rebut the said contention, in Paragraph 5 of counter - affidavit filed by the second respondent, he had stated that the grounds of detention was served on the detenu by the Superintendent, Central Prison, Madras and that the detenu was lodged in Central Prison and the contention that the detention order was not served through the Superintendent was not correct. It is significant to note that the counter is silent about service of the detention order and even in the detention order, the service is directed to be effected through the Superintendent, Central Prison, Madras. It is seen from the grounds of the detention order that the detaining authority has mentioned that he was aware of the fact that the detenu was on bail in a case in P.E.W. Minjur Police Station Crime No. 1354 of 1987 and would be proceeded with under normal Law. It is seen from the grounds of the detention order that the detaining authority has mentioned that he was aware of the fact that the detenu was on bail in a case in P.E.W. Minjur Police Station Crime No. 1354 of 1987 and would be proceeded with under normal Law. It has been repeatedly held by this Court that as regards the whereabouts of the detenu on the date when the detention order was passed, it is a material factor and in view of the fact that it is mentioned in the body of the detention order that he was on bail, but in the footnote both in the detention order as well as in the grounds of detention, the service is directed to be effected though the Superintendent, Central Prison, Madras, it clearly shows that the detaining authority was not sure as to whether the detenu was on bail or he was in custody on the date when the order was passed and the said doubt in the mind of detaining authority, clearly shows that there was non-application of the mind on the part of the detaining authority and he has passed the order mechanically. In these circumstances, the order is vitiated on the ground of non-application of mind. For the reasons discussed already above, we have no hesitation in holding that as regards the whereabouts of the detenu on the date of the passing of the order, there was non-application of the mind on the part of the detaining authority and he has passed the order mechanically and hence, the order is vitiated. 4. In the result, the writ petition is allowed. The impugned order passed by the second respondent detaining the detenu is hereby set aside and the detenu is directed to be set at liberty forthwith unless he is required in any other case.