You can sue. Whether you have a reasonable law suit based on good faith is something an employment attorney can answer for you. Before you call one and schedule a consult, get all your facts (and evidence) together. That way, you'll have a productive first meeting.
CA only has the power to suspend your driving privilege in CA. If MA learns of your CA problems, it may take its own action. It is never definite whether one state will notify your state. I suggest you complete the DUI school in CA. If you perform the DUI school in MA, you surely will be putting MA on alert. I strongly suggest you keep an eye on the mail at the address listed on your MA license. If MA takes action against you, it will notify you by mail at that address.
To begin, a 48A is a dismissal, not a filing. Second, it's rare that the Attorney General would agree to file a felony drug possession. So, if your case was dismissed with a 48A and you sealed (not expunged) it, it would not appear on your record for most purposes. If your case was filed, the one year has passed since it was filed, and it was sealed, then the same would be true. However, if the FBI was searching your record for certain purposes, then it might be able to "see" your record...
The Apprendi line of cases make it clear that at least on the Constitutional (US) level, the State does not have to prove the prior conviction beyond a reasonable doubt. Typically, most states have enhanced penalties for multiple DUI convictions and once the State proved the DUI, it need only present evidence (certified record of prior conviction) to satisfy their burden.
It appears that your 4 semesters of law school paid off. Your fact pattern does not seem to suggest the officer had probable cause or reasonable suspicion to stop you. Perhaps the officer might argue that limos in his jurisdiction are required to have a sticker or some other form of identification (similar to the tags on your license plate) and your limo didn't have such a sign. On your facts alone, it sounds as if maybe the officer was trolling for prostitutes and older limos tend to be the...
A DUI conviction is not typically a basis for removal for a lawful permanent resident from the US. There is a US Supreme Court case on point. However, it sounds as though you are not a LPR and have no status in the US. If that's the case, the immigration official has discretion. You should consult with an immigration attorney in your area as soon as possible.
If the police officer believed that he had sufficient evidence to arrest you for DUI, he would have arrested you for DUI at the time he stopped you. Even if he could change his mind today, which he probably could not, he would be admitting to allowing you to drive away while he believed you were drunk. It's tough to imagine any police officer would make that admission.
Go to court on Monday with a lawyer. If you don't go to court with a lawyer, ask the judge to appoint a lawyer for you. Whatever you do, make sure you (1) go to court on Monday, and (2) do not saying anything about your case until you have a lawyer. Jail isn't the only problem you need to be thinking about on the day before your first court appearance. You are too young to end up with a criminal conviction on your record if you can avoid it.
Your first conviction can only be used against you if you go to trial. Until that time, the police have the authority to amend the charge to first offense if they choose to do so. If you go trial on the second offense charge, then the State will have to prove that you were once convicted within the preceding five years of the latest charge. You should consult with an attorney who will advise you whether your case should be tried or whether you should negotiate a disposition other than trial.
It sounds as though the police gave your mom a summons for her alleged violations but did not take her into custody. Perhaps that's how police handle shoplifting in your mom's jurisdiction. If the police gave her papers, you should study them carefully as they may contain notice for her to appear in court. If she has nothing telling her what to do, it may be best for her to ask the police department that came to the store when she was detained. I don't think asking the store questions is a...