Well there are a number of different issues. First is addiction.
Alcohol and tobacco are both PHYSICALLY addictive, as opposed to marijuana, which is for the most part HABBIT FORMING. Marijuana won't send you into severe physical withdrawal symptoms. Tobacco is addictive on a level seen most often for illegal drugs like heroin. Alcohol is less so, but once your body becomes dependant, quitting cold turkey can literally kill you.
Look up the effects of alcohol use on the liver and brain.
Look up the effects of tobacco on heart disease and cancer of the lungs, throat, bladder, pancreas and kidney.
It's a red herring anyway. When I hear someone argue that marijuana needs to be illegal, removing the "health" argument is quite easy. Bring up, for instance, the hypothetical case of a person who smokes through a vaporizer, which removes 95% plus of the cancer causing tar. I actually know a number of people who do this, so it's not purely hypothetical. In this case, the negative health effects of marijuana are far less than tobacco. When I've brought this up in the past, people still resist legalization. I just have trouble believing the larger argument is really about the government protecting the health of its citizens.
Last I checked tobacco was the #1 cause of preventable death in the U.S. and the death toll was up somewhere around 10 million, although I think that is worldwide. How many people have died from marijuana? And why isn't my government protecting me from alcohol and tobacco, which is much more of a threat to my well being?
In terms of intoxication and loss of judgement, in terms of pain and damage caused by loss of judgement, alcohol is king. I have never seen one of my buddies smoke a joint and then want to go out and stomp on somoene. On the other hand, I've seen all manner of horrors perpetrated by drunk idiots who are completely out of control.
