No ethical attorney would 'guarantee' you success, although having a reputable immigration attorney represent your father would certainly improve his chances of prevailing.
Gunda J. Brost Brost Law Office This advice does not form an attorney-client relationship and is merely informative. It should not by itself be relied upon to address a legal concern.
You are best advised to hire an immigration attorney. Only death and taxes are guaranteed.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter,not should it be viewed as establishing an attorney client relationship of any kind.
Apparently your father represented himself when submitting the N-400. He may do the same in the N-336 process. An attorney can guide your father in the process including applicability of any available waivers. An attorney cannot guarantee the results anymore than a doctor can guarantee a treatment will be successful. It is ethically improper for an attorney to guarantee results and an attorney certainly cannot know the decision of the CIS adjudicator before the adjudicator decides.
Attorney Robert Brown's (former INS Director, 1972-99) reply to your question is general in nature, and does not constitute legal advice as all facts are known to him. For specific advice or representation you should retain an attorney experienced in immigration law. Mr. Brown's reply on AVVO does not create an attorney/client relationship not constitute legal advice.
Attorneys are subject to certain rules, which prohibit us from guaranteeing results or the outcome of a case. In order to naturalize as a US citizen, your father must either comply with all the requirements, including the one that calls for him to be able to speak, read and write English, or determine if he is eligible for a waiver of that requirement. An attorney can help determine eligibility and prepare the necessary waiver.
Answers provided by Ksenia Maiorova, Esq. on Avvo.com are of a general nature and do not constitute legal advice.
First off, no attorney can guarantee anything. If he or she does that should be your tip to say "thank you" and move on.
Second, generally speaking under these facts it appears there is no viable basis for an appeal. Unless your father is exempt from the English language requirements he is ineligible because he failed the naturalization examination. This cannot be changed on appeal. However, the denial of his application is without prejudice to filing of a new one.
Knowing all of the issues before he filed for naturalization by consulting with a Board Certified Immigration attorney may have saved him a lot of time and money. I suggest that he do so now before possibly wasting more of each by filing an appeal.
While this answer is provided by a Florida Bar Certified Expert in Immigration and Nationality Law, it is for general information purposes only and an attorney/client relationship is neither intended nor created. You should seek out qualified counsel to review your case and provide you with advice specific to your situation. Review Mr. Devore's Avvo Profile for more information about his expertise in immigration law and how to contact him to discuss your case.