Thousands of protesters took to the streets in Morocco on Sunday to demand sweeping changes to the nation's constitution, defying predictions that this thousand-year-old monarchy would prove an exception to the demands for greater democracy that are sweeping the region.

In Rabat, the capital, a crowd of up to 10,000 people marched through the streets chanting: "Down with autocracy" and "The people want to change the constitution," as well as slogans against the government, corruption and state television.

Morocco...