@Imnotrussian,
Those other impacts are the result of irresponsible decisions made by
some drug users, and are of course not necessarily caused by any drug use.
Hepatitis and HIV would be a problem with or without drugs being legal; as would uninsured patients, domestic violence, DUI, and crime. You're right, there may be a positive correlation between drug use and engaging in dangerous activities or making risky decisions, but there's no evidence to suggest that these things would get worse if drugs were legal, or that drug use would increase just because they are legal.
If you want some hard evidence for negative effects on our society
because of drugs being illegal, simply look at our prison, law enforcement, and courts systems. We are spending enormous sums of money on legal fees and prison expenses that go along with processing and imprisoning so many people for drug crimes. This is in addition to law enforcement efforts nationwide devoted to going after drugs. The percentage of our population in the prison system is astounding, and this is mainly a result of the drug laws. Courts and state's attorneys and public defenders are backed up with an endless supply of drug cases. This is clearly all because drugs are legal. And having these laws and prosecuting people does not seem to be stopping anybody from getting drugs or using them.
If you want some harmful effects that go along with drug illegality, try unconstitutional searches of home, person, and property that take place all the time, police brutality, fines, spending time in prison, all because a person wanted to get "high". And that's really what it's all about, and why drugs will never become legal in this country. The public is uncomfortable with others "getting high" and having a better time than they might have; The politicians are afraid of the rebellious actions and ideas associated with drug users, so they want a way to lock them up. (and win votes by telling us how they will save us all from the dangerous drug addict) How many political activists in the 60s and beyond have been prosecuted for drug crimes, because it was the only method the govt. had available to silence free speech?
The negative effects of drugs being illegal are much worse.