Can my employer change my health insurance to an inferior plan without giving me notice. Do I have any recourse?

If you are an at will employee, an employer is able to change the terms and conditions of your employment, including the nature and extent of the benefits offered, for any reason or no reason and without pre-notice. That is basic employment law. As to whether that general rule is modified by certain statutory provisions that apply to employee benefit plans where your employer is the plan administrator, the issue is not as clear. That said, you need to consult with an attorney who has a special emphasis in employee health plan law, usually known as an ERISA specialist. There may be notice provisions upon the change of coverage that arise out of ERISA or the Insurance Code that would apply to your employer if your employer is designated the Plan Administrator under your group health plan. Good luck to you.

One thing is for sure, the employer cannot threaten to fire you for not signing an insurance form! I'm pretty certain that's a violation of at least one law (ERISA), if not several. As for changing policies, the employer can DECIDE to terminate insurance coverage without implicating his or her fiduciary duties under ERISA, but the WAY the plan is terminated may be a violation of employer's fiduciary duties (which is a breach and actionable). The "plan document" is something the employer is required to have and required to give you on request. You can request the old one and the new one and review those for your rights. However, the way employer is acting makes me think you might not get them! As for what you can do, I'd have to hear more but I think you could get the documents with a letter from an attorney's office -- that usually grabs their attention. But you may have a right to sue too. You likely need an ERISA attorney.