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Looking at porn and the like that has to do with unknown and non-Muslim individuals is haram, given that it arouses one's lust and is seen with the intention of taking pleasure, or if it leads to the person committing other sins; this ruling is the same amongst all scholars. The only difference of opinion is that some of the maraje' believe that even if looking at these images and the like doesn’t arouse lust and isn’t with the intention of taking sexual pleasure or doesn’t lead to any other sins, it is still haram, and in other words, they consider it absolutely haram. Other maraje', such as the Grand Ayatullah Bahjat contrast between porn movies and porn images; the movies are absolutely haram, meaning that it doesn’t make a difference if it arouses or not; if the people shown in it are Muslim or not; if they are known or not, and if the movie leads to other sins or not.
We would like to draw your attention to two istifta's (fiqhi questions from the offices of grand ayatullahs):
1- Q: What is the ruling on watching bad movies (in which the actors are non-Muslim) if it doesn’t arouse one's lust?
A: All of the maraje' except for Ayatullahs Sistani and Tabrizi say that since it arouses one's lust and leads to other sins, it is haram.
Ayatullah Tabrizi: Watching movies that arouse one's lust towards committing haram acts or spread corruption and perversion among society are haram.
Ayatullah Sistani: Watching with lust and with the fear and possibility of it leading to other sins is haram.
2- Q: When working on the internet, sometimes there are bad pictures next to the articles we are reading, that we have no choice but to see, what are we supposed to do?
A: Imam Khomeini, Tabrizi, Khamenei, Sistani, Fazel and Vahid: If you just happen to see them unintentionally, it is okay, but looking at the images with the intention of taking lustful pleasure is haram; also, looking at them without such an intention, yet with the fear of looking at them leading to other sins, according to obligatory precaution, is haram.
 An istifta' from the offices of Grand Ayatullahs: Khamenei, Bahjat, Makarem and Fazel.
 An istifta' from the office of the Grand Ayatullah Khamenei.
 An istifta' from the office of the Grand Ayatullah Bahjat.
 Khamenei, Ajwibatul-Istifta'at, question 1187; Safi, Jami'ul-Ahkam, vol.2, pg.1717; Fazel, Jame'ul-Masa'el, vol.1, questions 1729 and 1731; Makarem, Istifta'at¸vol.1, question 778 and 782; and istifta's from the offices of Grand Ayatullahs: Nouri, Imam Khomeini, Bahjat, and Vahid.
 Tabrizi, Istifta'at, issues 1603 and 1605; Sirtul-Nijah, vol.5, issue 1129.
 Sistani,org (movies), Question 4 (farsi).
 Imam Khomeini, Ta'lighat alal-Urwah (Ahkamul-Takhalli), issue 2; Makarem, Istifta'at, vol.2, pg.1033 and Ta'lighat alal-Urwah (Ahkamul-Takhalli), issue 2; Safi, Jame'ul-Ahkam
 Seyyid Mojtaba Hoseini, Risaleye Daneshjouyi¸ pp. 205-206.