This feels like it can't possibly be true as written. Given that France has a court of appeals, that rather suggests that you can disagree with a judgement.
Your argument would also suggest that continuing to maintain your innocence after being found guilty would mean you're committing a further offence.
Typically in adversarial systems you can disagree with the judge and jury's findings in public as long as you abide by them; the idea that the judge creates justice and cannot be criticised comes more from inquisitorial traditions, as I understand it.
"Any attempt to publicly discredit a judicial act or decision—through actions, words, writings, or images of any kind—under circumstances likely to undermine the authority or independence of the judiciary is punishable by six months’ imprisonment and a fine of 7,500 euros.
The provisions of the preceding paragraph do not apply to technical comments or to acts, statements, writings, or images of any kind intended to seek the reversal, annulment, or review of a decision."
You are free to disagree with the ruling, but you cannot say that the trial is a parody of justice, the judge biased and the whole thing a conspiracy (cough cough Sarkozy)