Is it even possible under state/federal law? What kind of attorneys would be most useful?
Criminal Defense Attorney
If you are referring to a 17 year old as a child, then yes a 17 year old can be convicted of carnal knowledge of a juvenile in Louisiana.
Estate Planning Attorney
Carnal knowledge of a juvenile (Louisiana Revised Statutes 14:80 and 14:80.1) requires that the offender be seventeen years of age or older. It pertains when the victim is aged 13 to 17 and there is an age difference of two years or more (misdemeanor) or four years or more (felony). If the victim is under the age of 13, La. R.S. 14:42 (aggravated rape) applies. If someone is facing one of these charges, they should consult a criminal defense lawyer.
Workers' Compensation Lawyer
A criminal lawyer.
Don't forget to check "Helpful" if I helped you out. This response is not intended to create an attorney client relationship and is based on the limited information available at the time of the response. Before acting on anything stated or referenced in this response you should consult with an attorney of your choosing and go over the specific details of your legal circumstances. My responses are also given in the context of the laws of the State of Louisiana. To the extent this comment involves principles of law governed by another state my comment merely reflects my opinion and should not be considered legal advice.