"If a divorce decree states the ex spouse should leave 100% of life insurance for the childrens' college fund, but the ex-spouse has a will stating differently with trust designed by an attorney, which governs? Does the will trump the divorce decree?"
The divorce decree should over-ride the will, but the actual answer may depend on the language in the divorce agreement, the will and state law. You're best off having the matter double checked by your matrimonial attorney. The divorce agreement could have included the actual details of what the insurance requirements are (including type and quality of coverage, not just amount). The agreement could also include a requirement that the ex-spouse who is required to maintain insurance submit proof of insurance to the beneficiary spouse. The best way to go if there is still planning possibilities (i.e. the divorce is still being negotiated) is to have an insurance trust set up with an independent trustee (CPA, bank, trust company) who will monitor the insurance coverage. This approach can protect everyone. The beneficiary spouse and children are assured that the right coverage is in place. The insured spouse gets the ability to have the insurance continue for new beneficiaries when the requirements under the divorce agreement end (e.g., spouse remarries, children are emancipated), etc.