Unfortunately, bad faith claims are not actionable under ERISA.
ERISA is a federal law that pre-empts state bad faith laws, including those of Illinois. If your disability benefits claim has been mishandled by the insurer, and ERISA applies, then you will not be entitled to bring a claim for bad faith. This can undercut your ability to obtain maximum damages in extreme cases, as bad faith claims often lead to significant damages (and sometimes, courts award punitive damages, which can further multiply the amount received).
In some limited cases, however, you may be able to bring a separate fraud claim against certain defendants. You’ll want to consult a qualified ERISA disability attorney in Chicago for an evaluation of your bad faith claims and how you might be able to strategize around the pre-emption issue.
Many common law fraud claims are pre-empted by ERISA as well — such a claim might only avoid pre-emption if you can show that the defendant owed you (and violated) a duty independent of the ERISA-covered plan.