Bipolar disorder, which used to be called manic depressive illness or manic depression, is a mental disorder characterized by wide mood swings from high (manic) to low (depressed). Periods of high or irritable mood are called manic episodes.
James Byrd, Jr. was not engaged in a federally-protected activity when he was lynched and killed. The Matthew Shepard Act expanded the 1969 Federal Hate Crime Law to cover these and other types of brutal murders.
There are both state and federal laws that prohibit hate crimes, but proving a motive or bias is very difficult. Any type of crime can warrant some form of punishment, from fines and short prison stays for misdemeanors to long term imprisonment for felonies.