In NY a convicted criminal defendant may not successfully sue his criminal defense attorney…unless he is exonerated.  That, or a reversal of the conviction [the ability to demonstrate "innocence"] is necessary.  In Wisconsin, the rule is in flux.  Here is a case which discusses, without deciding, when the statute starts to run: on the date of the mistake or on the date of the exoneration.  Instead, Wisconsin borrows the Pennsylvania statute of limiations, and dismisses the case.

STATE OF WISCONSIN
IN COURT OF APPEALS
DISTRICT II
Thomas P. Jasin,  v. Michael Best & Friedrich LLP,

"PER CURIAM. Thomas P. Jasin appeals from an order dismissing his legal malpractice action against Michael Best & Friedrich (MBF). The issue is whether the cause of action is time barred under the applicable statutes of limitation. Without addressing whether Wisconsin would adopt an exoneration or two-track rule in determining when a criminal malpractice action accrues, we affirm the order of the circuit court based on the application of Pennsylvania law. " "In Pennsylvania, periods of limitation in a criminal malpractice action begin to run at the time the attorney-client relationship is terminated. Bailey v. Tucker, 621 A.2d 108, 116 (1993). Although Pennsylvania makes actual innocence an element of proof for recovery, it does not make exoneration a prerequisite to the accrual of the malpractice action and the limitation period may expire before the defendant has obtained postconviction relief. Id. at 115 n.12, 13. Jasin’s claims are time-barred under Pennsylvania law. Because we borrow Pennsylvania law regarding limitations, we need not address whether Wisconsin would adopt the exoneration or two-track rule of accrual"