rabbi, i want to understand hasagas gevul for the world i actually live in. the gemara (bava basra 21b) fights over whether a resident can stop another jew from opening a competing business in his alley, and the poskim fight over when the rule applies at all. but the whole framework assumes a town. in tech anyone can copy anyone overnight, and the market is the whole world.
1. the core case. rav huna lets a resident block a competitor from another alley, and rav huna brei d’rav yehoshua says once someone from outside sells in town, nobody can block anyone. which side does halacha follow, and is the logic about fairness to the first guy or about the town’s needs?
2. copying as a category. is improving on someone’s product competition or encroachment? if i build the same app but better, and his users come to me, did i do an issur, or did i do exactly what rava blessed in teachers, kinas sofrim tarbeh chachma, the jealousy of scribes increases wisdom? where is the line between winning and stealing his livelihood?
3. jew and non jew. does hasagas gevul even apply against a non jewish competitor, and does it protect me from one? or is the whole sugya internal to klal yisrael?
4. the market question. the gemara’s market is a courtyard and an alley. mine is a worldwide app store where “my town” is everyone. does halacha scale the courtyard to the market, or does the din simply not apply when there is no shared street?
bottom line, is hasagas gevul a live issur today or a museum piece, and if it is live, what does it actually forbid me from doing?
The first thing to clarify is that the Halachah does not generally give the first businessman a monopoly. The Gemara brings Rav Huna’s view that the first mill owner can stop another mill from opening near him because קא פסקת לחיותי, you are cutting off my livelihood. But Rav Huna brei d’Rav Yehoshua disagrees, and that is essentially the view we follow. The Shulchan Aruch rules that if one local resident has a store, mill or bathhouse, another local resident may open the same business and the first cannot say, “You are taking away my livelihood.” The Aruch HaShulchan explains the principle very simply: כל אדם יש לו רשות לעשות איזה מלאכה שירצה, every person has the right to engage in whatever occupation he chooses. (C.M. 156:5; Aruch HaShulchan 156:6.)
There was a separate protection against an outsider coming into another town and competing with the residents who supported that town and paid its taxes. But that was built around an economic world of separate towns and local markets. The Aruch HaShulchan himself says that an old rule of חזקת ישוב ceased to apply in his time once governments allowed Jews to settle freely wherever they wished, and he says explicitly that these matters have to be judged בכל מדינה ומדינה לפי הענין, according to the circumstances of each place. A later Tel Aviv Beit Din similarly held that where a profession such as insurance is not tied to a particular neighborhood, the old geographic distinctions do not fit in the same way. That logic is even stronger with an app whose marketplace is essentially the entire world.
So if you build an app and I independently build a similar app that is faster, cheaper or better, I do not see why you own that market. Competition is part of business. Chazal themselves sometimes preferred competition when it benefited the public, most famously קנאת סופרים תרבה חכמה with teachers, and the Shulchan Aruch even records circumstances where outside merchants cannot be excluded when their merchandise is better or cheaper for the Jewish customers. Of course, copying someone’s actual code, stealing confidential information, impersonating his brand, violating a contract, or taking something that is already effectively his is a different question. The Gemara’s case of putting your fishing net where the fish are already heading into somebody else’s net is a good example of the difference between ordinary competition and grabbing something that is practically already in another person’s hands.
The non-Jew question is also not completely black and white. The classic rules in C.M. 156 are largely rules governing Jewish communal commerce. The Rema even records a dispute concerning two Jews competing for the established business of a non-Jewish customer, so the fact that the customer is a non-Jew does not automatically make every form of interference permissible. But I would not turn hasagat gevul into a universal monopoly right protecting every businessman in the world from competition. Other laws such as theft, contracts, fraud, intellectual property and dina d’malchuta may still apply independently.
So is hasagat gevul alive today? Yes, but in a much narrower sense than people sometimes use the expression. It can still matter when you deliberately invade something that another person has already substantially secured, or where your conduct is designed to destroy his livelihood rather than simply compete. But in the normal modern marketplace, and certainly in a worldwide app market, the fact that somebody thought of the business first does not give him ownership of the field. If you can legitimately build a better product, build it.