State law requirements which impose different or additional requirements on pleadings filed in federal court are not enforceable if they conflict with the Federal Rules of Civil Procedure, even if the state law would qualify as “substantive law.” Thus a Delaware law which required the filing of an affidavit of merit with a medical malpractice complaint is not enforceable if a medical malpractice complaint is filed in federal court.

The plaintiff demonstrated a genuine issue of material fact regarding the hospital's liability for medical malpractice under the theory of ostensible agency and did not need to show further reliance under the Grewe test.