Puzzled over 401(k) Beneficiary Rights

[Guest cole stevenson]

I'm looking for thoughts on the following beneficiary situation under a 401(k) plan:

While married, participant names spouse as primary and sole beneficiary on plan's beneficiary designation form. A few years later the marriage ends with a legal divorce. The divorce decree has general language that neither spouse will make claim to any portion of the other's retirement pension or savings plan benefits. The aforementioned beneficiary designation is never updated by the participant. Then, the participant dies.

Does the beneficiary form prevail? Or does the language of the divorce decree have an effect?

What if, instead of dying, the participant had simply re-married? What effect, if any, does this have on the "old" beneficiary designation that still shows his then ex-spouse as primary and sole beneficiary?

Thanks in advance for any thoughts or reactions.

Cole