Doesn’t it stand in the way of implementing a universal health care plan?
No. ERISA (the Employees Retirement Income Security Act) prevents a state from requiring that a self-insured employer provide certain benefits to their employees. However, a single payer plan would not mandate the composition of employer benefit plans – it would replace them with a new system that would essentially be “Medicare for All”. The state would require employers to pay a payroll tax into the health care trust fund. This is legal and is done now with taxes levied to pay for Medicare.