In a civil suit, you'd typically need "preponderance of the evidence", i.e. you have to convince the judge that it's more likely than not. In practice, the wor

In a civil suit, you'd typically need "preponderance of the evidence", i.e. you have to convince the judge that it's more likely than not. In practice, the worst data sellers will pretend to act legally, so they'll often admit in some fine print what they're doing. Also, if the judge asks the representative of the company whether the company is selling your data, the possible answers are "yes", "I don't know", or "no". The former two mean you win. The latter means the representative risks jail time if it later comes out that the company did sell the data.