Chametz of a Non-Jew
Chametz, a grain product made with a leavening agent, is forbidden for a Jew to own, benefit from, or eat on Pesach. There are certain laws that guide how a Jew who has interactions with a non-Jew who owns Chametz should proceed on Pesach.
Letting Workers Eat Their Own Chametz
- If a non-Jew brings his own Chametz into one’s property as long as the non-Jew is holding onto the Chametz the Jew doesn’t have to get rid of the Chametz.
- Whether or not one is home for Pesach, having a non-Jewish worker eat Chametz (which belongs to the non-Jew) in one’s property on Pesach is problematic if it is one’s responsibility to feed one’s worker or if one usually feeds him (such as a house maid in the house), however, if one never provides them with food it’s permissible for the non-Jew to eat Chametz in one’s house.
Storing Chametz of a Non-Jew
See the full page here Owning_Chametz_on_Pesach#Storing_a_Non-Jew.27s_Chametz
Buying Chametz for Workers
- One may not provide Chametz for workers to eat nor should one bring one’s workers to a Chametz restaurant even if one isn’t paying for the food. However, if the non-Jewish worker goes to the restaurant to eat it’s permissible to pay for his bill as long as one didn’t order the food for him.
Insuring Chametz on Pesach
- It is permitted for a Jewish insurance company to offer insurance to a non-Jew even if they include chametz in that insurance policy. The reason it is permitted is because the Jew does not really own the chametz. Even though it is forbidden for a Jew to accept the responsibility for a non-Jew's chametz that is only true when it is in the Jew's domain. However, there is no halachic issue with a Jew taking responsibility for chametz of a non-Jew in that non-Jew's property.
- It is permitted for a Jewish insurance company to offer insurance to a Jew even if that Jew includes chametz on Pesach in that policy.
Chametz Gift on Pesach
Smelling Chametz on Pesach
- It is forbidden to smell chametz of a non-Jew or Jew on Pesach to derive pleasure.
- One shouldn’t go out of one’s way to derive pleasure by smelling Chametz but if one is minding his own business one doesn’t have to leave the area where there is a smell of Chametz.  If someone is in the street and there's a chametz restaurant he doesn't need to go around not to smell the chametz food.
Eating at the Same Table
- One may eat at the same table as someone who is eating non-kosher if one puts down something which will serve as a designation that the two aren’t eating together (a placement or table cloth on one person’s area), however, one may not eat food at the same table as someone who is eating Chametz. 
Going on an Airplane on Pesach
- A person should be careful to tell them that he doesn't want to order the meals since they have chametz in them and it is forbidden to own chametz on pesach or he should order a kosher meal.
- A person sitting next to a non-Jew eating Chametz at his seat he shouldn't eat his meal at the same time on his tray since the trays are so close to one another.
- A person shouldn't eat kosher lpesach food directly on the airplane trays, rather they should put down some cloth and the food on top of that.
- Shulchan Aruch O.C. 440:3, Rabbi Sobolofsky at yutorah.org between minutes 6 and 8
- Shulchan Aruch O.C. 440:1, Rabbi Sobolofsky at yutorah.org between minutes 8 and 10
- Rav Yisrael Belsky on OU Pre-Pesach Webcast 5771 between minutes 64:30 and 67:30
- Magen Avraham 440:1 permits taking responsibility for a non-Jew's chametz when the chametz remains in the property of the owner. Chok Yakov 440:6 is only strict if the Jew once took the non-Jew's chametz and then returned it to his property, but if he never took it into his property it is certainly permitted. Mishna Brurah 440:7 agrees with the Magen Avraham. Rabbi Dr. Asher Weiss explains that based on the above sources a Jewish insurance company offering a policy for a non-Jew which includes their chametz is permitted.
- Rav Shlomo Zalman Auerbach in Halichot Shlomo 6:1 permits offering insurance for chametz since that merely entails paying for its loss or theft monetarily. It does not involve any responsibility to actually watch or guard the chametz. Therefore it is not similar to the prohibition for a Jew to take responsibility for chametz on Pesach.
- Rav Yisrael Belsky on OU Pre-Pesach Webcast 5771 between minutes 67:30 and 68:30
- The Biur Halacha 443:1 s.v. afilu writes that smelling a non-Jew's chametz on Pesach is a discussion of the achronim. Some say it is forbidden since even chametz of a non-Jew is forbidden from benefit, while others say that there's no prohibition of smelling something that is forbidden from benefit unless it is designated for smelling (Rashba 3:234, S"A YD 108:6). However, the Biur Halacha points out that whether bread is considered designated for smell is a dispute of the rishonim (Rama OC 216:14). Biur Halacha concludes that it is forbidden for two other reasons: some say that smelling something forbidden from benefit like eating it if it is forbidden in any amount like chametz. Also, there's a concern that one will come to eat it. Ben Ish Chai Tzav 39 concludes that it is forbidden to smell chametz on Pesach.
- Rav Schachter on OU Pre-Pesach Webcast 5771 between minutes 76:30 and 78:30.
- Siddur Pesach Kehilchato v. 1 10:11 writes that there's no prohibition to smell chametz in a non-Jewish restaurant on Pesach if one isn't trying to get benefit. He explains that even if there's another path that would avoid it, it is permitted based on the principle of efsher vlo kmechaven (Pesachim 25b, see Bet Yosef YD 142:9 citing Ran A"Z 21a, Shach YD 142:34). Rav Shlomo Zalman in Halichot Shlomo 4:12 holds that one can't actively do an action to smell chametz on Pesach. See the footnote where he explains that the Rosh Pesachim 2:2 holds that if one is walking in a place where there is definitely a forbidden smell one should hold one's nose closed.
- Shulchan Aruch O.C. 440:3, Rabbi Sobolofsky at yutorah.org between minutes 13 and 15
- Shevet Hakehati 2:173
- Shulchan Aruch 440:3 cites the Rashba 1:177 who writes that it is forbidden to eat at the same table with a non-Jew on Pesach if they're eating chametz since it is probable that a crumb will fall into the Jew's food and a crumb isn't nullified on Pesach. The Shevet Hakehati 2:173 writes that this applies even to two tables where they are so close to each other like on people sitting next to each other on a plane. Nitai Gavriel Pesach v. 1 p. 245 56:7 quotes Rav Betzalel Stern who agrees but the Nitai Gavriel questioned it. Piskei Teshuvot 440:3 cites the Shevet Hakehati and Nitai Gavriel.
- Shevet Hakehati 2:173