In New York one must show "actual innocence" in a legal malpractice case arising from criminal defense by the target attorney. This standard is very difficult to demonstrate, and generally requires either an acquittal or reversal.  Here is a slightly different take from Connecticut, via the Legal Profession Blog.

"The lawyer had been retained to defend a murder charge. The defendant claimed innocence. The lawyer presented a theory of self-defense to prosecutors without the client’s authority and pressured him to plead to manslaughter, which he eventually did. The client got 20 years and filed the malpractice suit. About six months later, the client sought habeas corpus relief, claiming actual innocence.

A 29 day hearing was held on the petition. The trial judge concluded that the lawyer provided improper assistance, had misled the client on the terms of the plea bargain and sent the client a letter "replete with misstatements." Nonetheless, the trial judge found that the client had failed to demonstrate prejudice and was not entitled to relief.

Here, the court upheld the trial court’s finding that the prejudice component of the malpractice claim was "indistinguishable" from the finding of the habeas court: "