The "domino" argument against mercy killing says that, if sanctioned, mercy killing would .

According to the “domino” argument against mercy killing, mercy killing would set a dangerous precedent if sanctioned.

During the 1950s to the 1980s, a theory that was prominent was the domino theory. Based on this theory, it posited that if a country in a region is under communism’s influence, then the nearby countries would start to follow in a domino effect.

it's the under parts of the car