The person across the desk may be a licensed attorney, a DOJ accredited representative working at a recognized nonprofit, or somebody with a business license, a printer, and a sign in the window. All three can fill out a form. Only two of them can lawfully advise you on which form to file, what it will do to your status, and whether filing at all is a good idea in your situation. The difference is not a matter of skill or sincerity. It is a matter of authorization, and it is checkable in about ten minutes.
The licensed attorney, and the record behind the license
An attorney is admitted to the bar of at least one state, and immigration law being federal, admission anywhere in the country allows practice before U.S. Citizenship and Immigration Services and the immigration courts. That means a lawyer licensed in Texas can represent you in Ohio, which is legitimate and common. What matters is that the license is real, current, and clean. Every state bar keeps a public directory, usually searchable by name and license number, showing admission date, status (active, inactive, suspended, resigned), and any public discipline. Search the bar of the state the lawyer names, not a general web search.
Read the record slowly. A status of active with no public discipline is what you want. Inactive means the person is not currently authorized to practice, which sometimes reflects a retirement or a move and sometimes reflects something else. Suspended is a stop sign. Disbarred is a wall. If the directory shows discipline, most states link the underlying order, and it is worth the five minutes to see whether the matter involved client funds, missed deadlines, or an argument with another attorney. Also confirm that the name on the retainer agreement matches the name in the directory.
The accredited representative, and the organization behind the accreditation
The second lawful category comes from a Department of Justice program administered by the Executive Office for Immigration Review, generally called EOIR. A nonprofit applies to be a recognized organization, and individuals at that organization apply to be accredited representatives. Accreditation comes in two levels: partial accreditation covers practice before USCIS, and full accreditation adds representation in immigration court. These are not lawyers, and they are not pretending to be. They are trained non-attorneys authorized to do specific work at a specific nonprofit, often at low cost or no cost, and many of them handle high volumes of family petitions and naturalization applications competently.
EOIR publishes a roster of recognized organizations and accredited representatives, updated periodically and available free on the agency's website. Confirm three things there: that the organization appears, that the individual appears under that organization, and that the accreditation level covers the work you need. Accreditation attaches to the person at that employer, so someone who leaves a recognized nonprofit does not carry the credential to a private storefront. If a representative has moved, the credential has to be reestablished at the new organization before it means anything for your case.
Why the word notario carries a different meaning here
In much of Latin America, a notario publico is an attorney with additional credentials, trusted to draft and certify significant legal documents. In the United States, a notary public is a person authorized to witness signatures and administer oaths, with no legal training required and no authority to give advice. The overlap in sound has been the engine of a great deal of harm, and the Federal Trade Commission, which is responsible for policing deceptive practices against consumers, treats notario fraud as a recognized category of it. Several states now prohibit non-attorneys from advertising with the term at all.
The practical test is simple. Ask directly whether the person is a licensed attorney or a DOJ accredited representative, and ask for the state of licensure or the name of the recognized organization. Someone in either lawful category will answer immediately, because both answers are public anyway. A translator, a typing service, or a tax preparer can help you understand English text or type what you dictate, and that is genuinely useful work, but the moment the conversation turns to which category to file under, you need one of the first two.
Keep what you find. A screenshot of the bar record showing active status, or the EOIR listing showing the organization and accreditation level, dated the day you checked, costs nothing and settles any later question about who you hired and what they were authorized to do.