In that case, a key difference between an NDA and blackmail is that the former fulfils the requirements of a contract, while the latter does not (and not merely by being a currently illegal act).
With an NDA where the information is already shared, the party who would prefer that it go no further proactively offers something in return for the other’s continued silence. Each party is offering a consideration to the other.
If the other party had initiated the matter by threatening to reveal the information unless paid off, there is no contract. Threatening harm and offering to refrain is not a valid consideration. On the contrary, it is the very definition of extortion.
Compare cases where it is not information that is at issue. If a housing developer threatens to build an eyesore next to your property unless you pay him off, that is extortion. If you discover that he is planning to build something you would prefer not to be built, you might offer to buy the land from him. That would be a legal agreement.
I don’t know if you would favour legalising all forms of extortion, but that would be a different argument.
In that case, a key difference between an NDA and blackmail is that the former fulfils the requirements of a contract, while the latter does not (and not merely by being a currently illegal act).
With an NDA where the information is already shared, the party who would prefer that it go no further proactively offers something in return for the other’s continued silence. Each party is offering a consideration to the other.
If the other party had initiated the matter by threatening to reveal the information unless paid off, there is no contract. Threatening harm and offering to refrain is not a valid consideration. On the contrary, it is the very definition of extortion.
Compare cases where it is not information that is at issue. If a housing developer threatens to build an eyesore next to your property unless you pay him off, that is extortion. If you discover that he is planning to build something you would prefer not to be built, you might offer to buy the land from him. That would be a legal agreement.
I don’t know if you would favour legalising all forms of extortion, but that would be a different argument.