How and why you were charged with a felony is less important than what you were convicted of. If you were convicted of a felony, your subsequent successful return to court to get exempted from sex offender registration does not change the felony nature of the conviction, or mean that the conviction was improper. Someone would need to review transcripts of your plea and/or sentencing hearing(s) as well as the subsequent hearing(s) dealing with your exemption from the registry to determine whether you have any options. The law favors finality, so you could pay for the transcripts and for someone to review them only to find out you don't have any viable options. Good luck.
This answer is provided for general information only. No legal advice can be given without a consult as to the specifics of the case.
I don't know who told you that the only reason for the felony is because of registration, but they're dead wrong. The reason you were charged with a felony is because the District Attorney's office in your county believed that you committed that felony. Whether or not you must register as a sex offender is only decided after you are convicted of the crime. And as to "where it should be" . . . with all due respect, you registering or not registering for the registry doesn't change whether or not you committed a second degree sexual assault. If you entered a plea to that charge, you told the Court on the record and in front of the general populace that you committed the crime. So "where it should be" is what you admitted to, assuming that's the case.
Since you said this is years later, I'm not sure your right to appeal this case even exists; while the sex offender registry could be viewed as a technical aspect that could be modified, the actual conviction isn't as technical. Under the law you have 20 days to appeal your sentence or the right to appeal is waived forever. Absent a complete miscarriage of justice -- a standard which is almost never met unless the DA's office genuinely screwed things up -- if you failed to appeal at the time or you appealed and lost, that's the end of it.
You can certainly pay for the transcripts and hire a lawyer and review everything about your case, but do so with the understanding that there's very likely almost nothing that attorney can do for you. Your only options at the moment -- at least from where I see it, albeit without the facts of your case -- are to ask the DA's office to reopen the case and amend it to a misdemeanor (which they're almost always unwilling to do) or request a pardon from the governor (which Governor Walker refuses to do, though the next Governor might). So I'm afraid you might be out of luck on the amendment.
I agree with my colleagues.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
You should seek out a local attorney and sit down with them to see what if any remedies you may have.
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