Mr. Tuer was to have coronary artery bypass graft surgery. Prior to the surgery, Mr. Tuer was having chest pains and was prescribed Heparin to help with the pain. As was protocol at the hospital, he stopped being administered Heparin on the morning of the surgery because it was not good to have the drug in his blood during surgery. Right before the surgery, Dr. McDonald (defendant) was called away to an emergency with another patient. This postponed the surgery. Dr. McDonald considered restarting the Heparin for Mr. Tuer, but he decided not to because of the danger of having the drug in the blood during surgery. Approximately four hours later, before the surgery began, Mr. Tuer went into cardiac arrest. Mr. Tuer died the next day. After Mr. Tuer's death, Dr. McDonald and the hospital changed the protocol of discontinuing Heparin the morning of surgeries. Under the new protocol, a patient would receive Heparin right up until being taken into the operating room. Mrs. Tuer (plaintiff) filed a medical-malpractice suit against Dr. McDonald. She tried to introduce evidence of the subsequent remedial change in protocol under either a feasibility or impeachment theory. The Circuit Court for Baltimore County barred the evidence, and a jury found in favor of Dr. McDonald. The Maryland Court of Special Appeals affirmed. Mrs. Tuer appealed.