How do you sue insurance company for full benefit of disability?

If you qualify for a DI payment under the terms of the contract, you should not have to sue. You just should have to simply file a claim with the claims department. Unfortunately not all valid claims are approved. If you obtained your disability insurance on your own, i.e. if it is an individual policy, then if all else fails to may sue the insurance company in state court, based on the laws of the state where you live. You should consult with a lwyer in your state about that since state laws do vary.

If you obtained your disability insurance through your employment, your claim is not subject to state law, but to federal law, under the Employee Retirement Income Security Act (ERISA). There are limited exceptions to this, such as if your employer is a church of a governmental entiry, but generally any employment-based coverage is governed by ERISA. Unfortunately ERISA is a very unfair law when it comes to enforcing insurance contracts, and you will find the deck is stacked against you in court (for further information see http:/problemiserisa.blogspot.com). You should still consult with an attorney, but you should make sure the attorney is well-versed in ERISA law, because it is highly complex and arcane and an inexperienced practitioner would have a difficult time getting up to speed.