Visa was not a plaintiff to a data breach lawsuit against Target and the involvement of a third party such as the credit card company is an unusual twist to the data breach litigation. But it could end up being a significant advantage for Target, which fought to keep the class certification papers under seal, citing the potential risk of another attack.

'It's best for Target not to be involved in the litigation because they won't be in discovery giving away more information than what's happened,' said Michael Sussmann, a partner in the privacy and data security practice at Perkins Coie in Washington, who is not involved in the deal.