And sorry for the confusion. Now I understand.
And small point, Marijuana is technically not legal in MA. The state has "decriminalized" small amounts (less than one ounce). It is still illegal, in the same way that driving
over the speed limit is illegal. But it is no longer a criminal offense.
Now, on to the question.
IL has significantly more stringent laws on possession of marijuana. It is a crime (misdemeanor
) to possess 30g or less of Marijuana. 30g is a bit over 1 ounce.
Possession of less than 2.5 grams of marijuana is a Class C misdemeanor, punishable by a jail term of up to 30 days.
Possession of between 2.5 - 10 grams of marijuana is a Class B misdemeanor, punishable by up to 6 months imprisonment.
Possession of between 10 - 30 grams of marijuana is a Class A misdemeanor for a first offense, which is punishable by a jail term of up to 1 year.
So this is a criminal offense.
And if he "pays the fine" he will have a criminal conviction.
So what are the options?
He can "pay the fine" if he likes...but as I mention, that would result in a conviction. It is a misdemeanor (not a felony) but it would likely show up on future "background" checks unless or until he has the arrest/conviction "sealed" (a separate process he would likely be eligible for).
Or he can go to court and "plea his case"
Now...you do not get into the specifics of the conduct that led to the arrest...it may be that there are grounds to contest the fact of the arrest and perhaps he could take this to court and force the government to prove the case beyond a reasonable doubt.
Or to have a lawyer try and negotiate a "plea agreement" on his behalf.
That is a cost benefit analysis he will have to make. Is it worth the time/expense to travel back to IL to resolve this.
If he does nothing, then the state will issue a warrant for his arrest.
So he will want to either pay the fine, or arrange to travel to IL to try and resolve this matter directly.
It is important to understand that the fact that he thought the law in IL was the same as the law in MA is no defense. They can still convict him even though he was mistaken about the law.