Different people have different opinions on this subject. Some say that Justin Bieber does sag his pants and they say that he does this in order to maintain his "gangster" image and style. Others say that he doesn't sag his pants at all.
Sagging is a fashion style which involves wearing any type of trousers (jeans, slacks, pants or shorts) below the waist. This means that they hang below the waist area and tend to reveal a great deal of the person's underwear. A person who sags their pants is called a "sagger".
This style of sagging generally tends to only apply to men who show their underwear. A woman who wears low-rise jeans that show off their underwear is not a sagger.
The origin of sagging is predominately unclear, although there are speculations the fashion statement first appeared in the United States prison system where the men were not allowed belts to hold their pants up. This was put in place to prevent any possible suicides from hanging. This style was adopted by hip hop artists in the 1990's and since then it has found its way into popular culture and everyday clothes particularly amongst young people.
The reaction to sagging has been generally negative. In the majority of schools, sagging pants goes against the dress codes and this movement has received constant support from courts. However, prior to the 2008 United States Presidential Election, Barack Obama appeared on MTV saying that the laws put in place banning sagging were a waste of time.
The town council of Delcambre, Louisiana passed an indecent exposure ordinance in June 2007 which prevented people from wearing their clothes in such an indecent manner that it exposed their underwear. And in March 2008, the city council of Hahira, Georgia passed a controversial clothing ordinance which prohibited people from wearing there pants below the waist so that they revealed their underwear or skin.