Thanks for reporting on the disparate levels of enforcement of marijuana laws across the country [“Entrenched in the war on weed,’’ front page, June 22]. Police call marijuana a gateway to hard drugs, implying that their tough enforcement of prohibition prevents problems with harder drugs down the line. Research does not support this idea.

The vast majority of marijuana users have never even seen heroin or crack cocaine. A small subset of people develop problems with hard drugs, usually as a result of life stressors and a genetic predisposition to these troubles. Some of them use marijuana before they use hard drugs; many do not.

Enforcing harsh penalties against marijuana users does not prevent problems with hard drugs; it simply wastes the time of law enforcement officers, clogs our court systems and drains tax dollars that could be spent on proven prevention programs.

Mitch Earleywine, Albany, N.Y.

The writer is chair of the executive board of NORML, which aims to reform marijuana laws.