Doe #151 was not listed in the original complaint : see page 26:

…
164. Defendant Doe 150, without authorization, reproduced Plaintiff’s registered work OverDrive (U.S. registration No. PA 1-660-158) and distributed it on April 4, 2010 from the IP address 99.156.120.197.

165.Defendant Doe 152, without authorization, reproduced Plaintiff’s registered work OverDrive (U.S. registration No. PA 1-660-158) and distributed it on May 20, 2010 from the IP address 12.24.59.130.
…

Nonetheless the IP for Doe #151 was listed in the 10/4/10 AT&T subpoena signed by the judge: page 5:

…
150 April 4, 2010 99.156.120.197 17:07:11
151 May 12, 2010 99.189.182.125 07:22:58
152 May 20, 2010 12.24.59.130 05:01:56
…

This is a Houston, TX address.

I have already covered one huge discrepancy in court filings. It did not take long to discover this one. One-two “honest” mistakes in a document that lists more than two hundred Does: is it such a big deal? It certainly is — for the victims of these errors. I’d like to remind that one of the most important cornerstones of the justice in this country is the Blackstone’s formulation:

better that ten guilty persons escape than that one innocent suffer

Also, I question the honesty of this error. A deliberate omission theory is very plausible: the IP did not have anything to do with alleged infringement, but someone wanted to unmask an AT&T customer for some other reason, to avenge for a harsh e-mail for example. Listing this IP in the complaint would be a potential disaster because no relevant evidence ever existed; but a discovery without formal claim can be easily explained as a mistake if someone discovers that an unrelated IP was smuggled into the ISP subpoena.

I don’t even want to think about the collateral damage in troll lawsuits where tens of thousands IPs are being subpoenaed.