Essential function of an ER nurse?

The obvious come to mind: assessment, lifting, medication administration, documentation, education, etc. But in an environment in which it is commonplace for nursing technicians, paramedic students (once competency has been demonstrated), and other individuals that hospital policy allows to obtain peripheral intravenous access or obtain venous samples via straight stick needle, are IV placement and phlebotomy tasks ESSENTIAL job functions of an ER nurse? Given that many state nurse practice acts detail and specifically name task delegation of appropriate nursing care functions to qualified, unlicensed personnel, do the physical actions of obtaining peripheral vascular access and venous samples constitute an "essential job function" of an ER nurse; or is the ER nurse's essential job function in regards to IV placement/venipuncture to verify its satisfactory completion, whether by the nurse them self or other appropriate care provider?