The right of a party to be represented in litigation by the attorney of its choice is significant, and disqualification of that attorney won’t be required just because that attorney has represented the opposing party in the past. Rather, there must be a violation or threatened violation of an ethical rule.
It’s natural that clients want their attorneys to give them at least some idea of the likely outcome of their cases. Certainly it’s part of the attorney’s job to give the client a sense of whether the matter is likely to be resolved successfully or it lacks merit. But attorneys should never give a guaranty.
When you’re hired to make an initial case evaluation, make sure you have an understanding with the client that, if you find that the case lacks merit, you won’t provide any further representation on it. A case may seem compelling to the client, but you may see a fatal flaw. Explaining this can be uncomfortable, but it’s critical that you do so in a termination letter that clearly states your position.