Other benefits:

Lower Crime Rates (Crimes commited by addicts)
Police time can be used more effectively elsewhere
Tax money
Users Health (drugs on the street have 'extras')

Downsides:

Drugs are bad (health etc)


In Liverpool, England Heroin was temporarily legalised and attainable at some Hospitals. Users were safe from gaining aids from needles and the drug itself was pure and safe. Also Crime rates dropped by a third