In a mass layoff, you have zero leverage therefore there's nothing to negotiate. You only have leverage if there's a a reason to keep you on the payroll or the

In a mass layoff, you have zero leverage therefore there's nothing to negotiate. You only have leverage if there's a a reason to keep you on the payroll or there's something you have that they want and, in a mass layoff, neither of those are probably true. If you have special extenuating circumstances (e.g. being on disability), you might try pleading for additional severance but it seems like a long shot. Regarding hiring a lawyer, read the documents you receive and then decide whether you need to hire a lawyer. Assuming their HR and lawyers were competent and no special circumstances apply to you (e.g. you're an executive or you have iron-clad proof of being discriminated against when being selected for the layoff), most likely all hiring a lawyer will get you is an explanation of what the documents mean and a large bill.