When was the punishment of a slap with a ruler in school banned?

The punishment of a slap with a ruler in schools, often referred to as corporal punishment, began to be banned in various countries during the late 20th century. In the United States, many states started outlawing corporal punishment in schools during the 1970s, with a significant movement against it gaining traction in the 1980s and 1990s. The exact timeline varies by country and region, but the overall trend has been towards banning such practices to promote positive disciplinary methods.