Your ISP will rollover on you in a New York Second.

Any "officer of the court" can issue a subpoena in a civil matter. A Plaintiff's counsel can issue a subpoena for ISP data with a discovery motion before trial. (US Laws.) The ISP will be in contempt of Court if they to not respond or motion to quash before that Court. What data may be handed over is regulated by local laws and then by the Court as relevant.

No ISP is going to incur legal expense over a piracy suit — they have no point to argue — piracy is an unlawful act ...

You want a link? Look up your local version of the Court Rules. This discovery and subpoena power may very some country to country.

Why believe me when you can spend money on lawyers ...