Legal Question in Wills and Trusts in California

Possibly, if the plaintiff proves (via the expert testimony of another attorney) that the first attorney's representation fell below the standard of care AND that X would have won the case but for the inadequate representation. And the attorney would have to have malpractice insurance or other money or assets from which a judgment could be enforced. Watch out for legal time limits (my best guess is one year from the date the last court case was lost).

It does not help us to be able to give anything more than a general statement of the law unless you give us the relevant facts of the case. Your question was can an attorney be sued for malpractice if he commits malpractice.

The question is whether the failure to investigate a little more was beneath the standards of care of the profession, i.e., professionally negligent. An attorney is not required to leave no stone un-turned, no grain of sand un-examined in every case. An attorney must balance the costs of investigation, and all their other legal work, against the budget of the client, the amount in controversy in the case, and numerous other factors to determine how much intensity, effort and expense a particular case warrants. If the attorney was negligent in not doing the extra investigation in light of all the facts, circumstances and financial realities of the case, then they are liable for malpractice. If they were not negligent, then you would lose a case against them.