1) Remember that severance is never required: some people (many, in fact) do not receive it, and when workers do get it, the amount they get is 100% up to the employer unless there was an in-effect written contract requiring it. There is no way to force the employer to give you more severance unless  they are violating the severance provisions of a contract. 2) 4 weeks notice requirement means that--even if it were enforceable (see  below)--that if you did not receive sufficient notice, you would get that amount of pay: e.g. 4 weeks (or another 3, since you did receive 1 week of notice). But you are receiving 10 weeks, or more than the notice period. Therefore, even if the notice period were enforceable, you are already receiving more than the notice period would give you and so the notice requirement would not entitle you to any more.3) Most employee handbooks are not enforceable because they contain language or terms limiting their enforceability. Any language like the below would make the employee handbook not enforceable: "All employment is employment at will"; "Policies subject to change"; "Nothing in this handbook creates a guaranty or contract of employment."4) When people do get severance, the two most common amounts seem to be 1 week per year of severance, or a base of 2 weeks plus an additional 1 week per year.