The Law is a Dark Room) is a 1981 Indian Tamil-language vigilante action film written and directed by S. A. Chandrasekhar, from a story by his wife Shoba.

The film stars Vijayakanth, Poornima Devi and Vasumathi, with Sangili Murugan, Nithin and Chowdry in supporting roles.

It was released on 14 February 1981, and became a major commercial success, inspiring more Tamil films with themes about the law system which were mostly directed by Chandrasekhar.

The film was remade in Telugu as Chattaniki Kallu Levu (1981), in Malayalam as Maattuvin Chattangale (1982), in Kannada as Nyaya Ellide (1982), in Hindi as Andhaa Kaanoon (1983) and again in Tamil under the same title (2012).

The trio's method of committing the murders with an alibi registers in Vijay's mind and he decides to take revenge on them in the same way.

But in court, she is unable to prove this as Vijay as built a strong alibi, showing he was in lock-up when the murder took place.

Vijay is exonerated due to lack of evidence, but Sheela remains determined to apprehend him in a higher court.

aanal adhu ezhaikku ettadha vilakku", which translates to, "[The] law is a dark room where the lawyer's argument is a lamp.

This casting choice attracted stiff opposition from some quarters protesting against giving the hero chance to Vijayakanth in the film.

[7] On 15 March, Nalini Sastri of Kalki called it a routine revenge story, but the director's treatment of the subject made it worthwhile.

[7] Sattam Oru Iruttarai was remade in Telugu as Chattaniki Kallu Levu (1981), in Malayalam as Maattuvin Chattangale (1982), in Kannada as Nyaya Ellide (1982) in Hindi as Andhaa Kaanoon (1983) and again in Tamil under the same title by Chandrasekhar's granddaughter Sneha Britto (2012).