Question :What are circumstances that might permit interest?
Answer:The following are circumstances That Might Permit Interest:
Land or Documents
Ribbis applies to lending land in order to receive more in return or the same land together with something else in return. This is considered biblical ribbis. Tosfos Bava Metsia 61a s.v. im holds that based on a klal uprat uklal land is excluded from the laws of ribbis. The Rosh b”m 5:1 and Ran b”m 61a s.v. karkaot agrees. Tur 161:1 cites Ri who agrees. Beis Yosef cites the Rabbenu Yerucham who is strict. The Rabbenu Yerucham 1:8 is citing the Rashba b”m 61a minayin, however, in our versions of the Rashba it seems in conclusion he is lenient. The Beis Yosef isn’t certain if there’s a rabbinic prohibition even according to Tosfot. Taz 161:1 says obviously there is a rabbinic prohibition. Certainly Tosfot adds that money to receive some land or benefit from land is forbidden. The Shach 161:1 and Taz 161:1 who point out that Shulchan Aruch 161:1 seems to be strict. See Gra 161:1 who might be lenient to consider it only a rabbinic prohibition.
Ribbis applies to money given in a document. The Rosh Bava Metsia 5:1 writes that theoretically documents should be excluded from ribbis because of a klal uprat. However, he notes that there’s no case of a loan with a document, giving a loan to receive it return with an interest on the side is a rental. Beis Yosef 161:1 asks why it isn’t considered a loan to give a document of debt that is worth 100 to receive in return a document of debt of 200. Bach 161:1 and Taz 161:1 both argue that such a deal would certainly be ribbis since the document merely represents money.
Mitzvos
Ribbis for Pikuach Nefesh
It is permitted to borrow from a Jew with interest in order to save someone’s life. That is only if borrowing from a non-Jew with interest isn’t an option that would allow saving the person’s life. The lender is doing wrong by lending with interest but nonetheless one doesn’t need to worry about causing him to sin if one is trying to save someone’s life.
This comes from the following sources: The Shulchan Aruch Y.D. 160:22 writes that it is permitted to borrow with interest in order to save someone’s life. Taz 160:21 is bothered what is the point since it is obvious that it is permitted to violate any sin (besides idolatry, illicit relations, and murder). Beis Lechem Yehuda writes that it is permitted to borrow with interest from a Jew even if a non-Jew is available but it’ll take longer and in order to save time one can borrow from the Jew if it is quicker and could impact saving the person.
Why does pikuach nefesh allow violating lifnei iver? Shulchan Aruch O.C. 306:14 rules that in order to protect someone from getting involved with a great sin it is permitted to sin a small sin, even if that involves violating Shabbat. If so we see that it is like pikuach nefesh to save someone from spiritual destruction. Why then is it permitted to cause someone sin in order to save someone else?
Tosfot Shabbat 4a s.v. vchi writes that the principle that one could save someone else from sinning by sinning oneself doesn’t apply if they entered the situation by negligence. This is codified by the poskim such as Magen Avraham 306:28 and Mishna Brurah 306:56. Rabbi Baruch Pesach Mendelson (Beis Yitzchak v. 39 p. 730 explained that there is no mitzvah of arvut when the person got into the situation of sin by his own negligence. Therefore, it is forbidden to save him from sin by sinning yourself.
Eretz Tzvi 2:20 writes that violating Shabbat to save someone from a violation of Shabbat isn’t pikuach nefesh. Otherwise the Gemora Shabbat 4a wouldn’t have had a safek about this. Also, Tosfot 4a says that we wouldn’t violate Shabbat if he was negligent but if it really was pikuach nefesh we would violate Shabbat even if he was negligent to become sick.