Why is using drugs illegal?

Bad drugs are because they are bad for you and could really mess up a person and could kill them.

Answer:

While some potent drugs are against the law equally potent drugs such as caffeine, nicotine, and alcohol are acceptable. This may be due to a cultural familiarity and acceptance or long use which has taught methods to handle a users "hits", or the fact that the government controls them through legal distribution systems and gains revenue from their sales.

In many countries drugs such as cannabis are becoming legal and in others, such as Portugal, laws controlling drugs have been repealed.