Such cases rely on identifying the machines the IP address of machines from which content was illegally downloaded as evidence of wrongdoing.
Experts have questioned whether the IP address is sufficient evidence because it identifies an internet connection rather than an individual.
An adult film studio (Malibu Media) must take cases to court, a judge has ruled. Malibu Media has instigated 349 mass lawsuits, 43 in Pennsylvania this year.
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