Standing in legal malpractice cases is determined by the question of privity.  Privity comes in several flavors.  One is whether there is a contract between client and attorney, written, oral, or implied.  If there is a contract, (even if the contract is implied from the factual representation which takes place), then that particular question of

Is it possible to prove legal malpractice at a trial which goes to the jury?  While an argument can be made that the attorney failed to call a particular witness, or failed to offer a particular piece of evidence, the countervailing argument will be that an attorney may choose among several different reasonable trial strategies

Frequently, clients discern mistakes make in their cases, and wish to start a legal malpractice case.  Unfortunately, departure from good practice is but one of the four elements of legal malpractice.  The merit of most legal malpractice cases is determined by analysis of the middle two points.  Was the mistake a proximate cause of damage