Legalization

• No real impact. Past legalization of other ‘drugs’ such as alcohol and tobacco have not lowered the amount of consumption nor has it significantly changed the outlook of people who do use these substances.
• Health effects. All forms of marijuana are known to be mind-altering drugs. Studies by many experts and psychiatrists have concluded that regular consumption of marijuana does lead to an increase in the potential for mental health problems. In fact, it has been known to lead to the development of schizophrenia in young adults and repeated and concerted use has proven to cause psychosis. Marijuana has also been linked with depression. 
• Youth encouragement. Legalization would increase the chances of the drug falling into the hands of kids.
• The legalization of the drug will encourage usage among youth and young adults, Legalization would only increase the chances of the drug falling into the hands of kids.
• It has been proven that early usage of marijuana is far more debilitating that alcohol as marijuana retards mental development.  It can not be guaranteed that restrictions on legal usage would ‘curtail’ or ‘regulate’ or even ‘educate’ young people.
• Taxation issues. Sure, advocates can say the government can regulate the usage of marijuana and would impose taxes on users and retailers. However coming up with the right tax structure and regulatory conditions is a monumental task. Just by levying too high a tax it could easily encourage growers to once again sell it on the black market and thereby render the move to legalize worthless.
• Chemically altered products. Much like the hazardous chemical cocktails that cigarette companies turned their products into, marijuana growers and manufacturers could be encouraged to do the same to increase sales and get customers addicted.
• Increase in crime.  With legalization comes the additional burden of having to deal with people driving their cars while high.  This is already a problem with alcohol.  Why compound it?
• It has "no accepted medical use."
• Impairment of thinking, problem-solving skills and memory

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•                 Reduced balance and coordination
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•                 Increased risk of heart attack
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•                 Heightened risk of chronic cough and respiratory infections
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•                 Potential for hallucinations and withdrawal symptoms

The Lungs.

 Marijuana smokers can have many of the same respiratory problems as tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, a heightened risk of lung infections, and a greater tendency toward obstructed airways.

Numerous studies have shown marijuana smoke to contain carcinogens ( any substance or agent that tends to produce a caner)and to be an irritant to the lungs.

In fact, marijuana smoke contains 50 to 70 percent more carcinogenic hydrocarbons than tobacco smoke. Marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers do, which further increases the lungs’ exposure to carcinogenic smoke.