I take it you are talking about an appointed attorney or public defender in a criminal case that went to trial. You are attempting to raise a constitutional issue of "ineffective assistance of counsel. A quick definition of this argument is from the link below:
"In Strickland v. Washington (1984), the U.S. Supreme Court declared that the Sixth Amendment guarantee of assistance of counsel means effective assistance. To prevail on an appeal based on the claim of ineffective assistance of counsel, the appellant (the person who appeals) must prove that his or her attorney's performance was deficient, that the attorney's substandard performance prejudiced the case, and that it was likely that, but for the attorney's errors, the result would have been different. Strickland puts the burden of proof on the appellant to prove that his or her lawyer's assistance was ineffective.".
In other words, you would have to prove that the pieces of information before the trial were so important they would have changed the outcome and that your attorney was incompetent in forgetting to raise them. This would be a tough, almost impossible burden, unless those pieces of information were incredibly compelling, like an alibi that was corrorborated by witnesses of unimpeachable character and backed up by surveillance camera footage, or something like that. Superhuman efforts are not required of a competent counsel and 20:20 hindsight is probably not going to get you where you want to be on an "ineffective assistance of counsel" claim.
On appeal the there is a presumption of competence that you have to overcome. You have to show there was a legal, or series of legal errors that prejudiced your case. These definitions are themselves complicated and can be difficult to apply without detailed facts.
You should contact a lawyer who can help address this on appeal if you still are within the appeals deadline.
Also, by putting information like this on the internet, be aware you may be waiving the attorney-client privilege.
www.court-martial.com; www.court-martial.us.com; firstname.lastname@example.org 703-298-9562, 800-401-1583. Answering your question does not create an attorney-client relationship.
Legal malpractice and negligence Criminal defense Burden of proof for criminal charges The 6th amendment and criminal defense Right to counsel in criminal cases Alibi and criminal charges Appealing a criminal conviction Constitutional law Professional ethics Lawsuits and disputes Civil rights Appeals