OPPONENT'S BRIEF
Factual Proposition: Consuming marijuana is detrimental to one's health.
Definition of key terms:

1. Consumption= Smoking or eating marijuana. 2. Marijuana= Psychoactive mind
altering substance, also known as cannabis. 3. Detrimental= Serious harm.

Primary Inference:

Smoking or eating marijuana is likely to create serious health problems
for most individual users or society.

Overview:

Since the 1920's supporters of marijuana prohibition have exaggerated the
drugs dangers. Many of the 'reefer madness' tales that were used to bring
support for early anti- marijuana laws , continue to appear in reports today.
The most important studies of recent times took place in the 1970's in Greece,
Costa Rica and Jamaica. These tests reported on the effects of marijuana on
its users in there natural environment. The reports covered marijuana's
effect on the brain, immune and reproductive systems. (1) These studies didn't
answer all the questions about the effects of marijuana on the user, but
supported the idea that marijuana for the majority of its users was not
detrimental to the health of the users brain, immune or reproductive system. In
looking at all the reports that are published there are perhaps, random studies
which may indicate greater toxicity of the drug. But in all of these cases, the
research was flawed or inaccurate since the findings cannot be duplicated by
other scientists.

Contention I: Marijuana does not damage brain cells.
A. Claim: Use of marijuana does not cause memory loss.
1. Grounds: In a recent study rhesus monkeys were exposed to the
equivalent of 4-5 joints per day for an entire year without any alteration of
hippocampal architecture.(2) Slikker, W. et al,' Behavioral, Neurochemical, and
Neurohistological Effects of chronic Marijuana Smoke Exposure in the Nonhuman
Primate,'pp219-74 in l. Murphy and A. Bartke (eds), Marijuana Neurobiology and
Neurophysiology, Boca Raton: CRC press(1992)
2. Warrant: Alteration in hippocampal structure results in memory loss.
3. Backing: A study reports ' Any alteration of the hippo campus, a
cortical brain region, results in negative consequences for learning and memory
in humans.(3) Heath, B.C. et al, 'Cannabis Sativa: Effects on Brain Function
and Ultra structure in Rhesus Monkeys, 'Biological Psychiatry 15:657 (1980).

B. Claim: Use of marijuana does not cause cognitive impairment.
1. Grounds: In a study it is reported "marijuana intoxication does not
impair brain related cognitive functions"(4)
Weckowicz, T.E. et al, "Effect of Marijuana on Divergent and
convergent Production Cognitive Tests," Journal of Abnormal Psychology 84:
386-98(1975)
2. Warrant: Studies have shown that marijuana does not effect brain
related cognitive functions.
3. Backing: Researchers have proved scientifically that marijuana does
not impair cognitive brain functioning include(5)Hooker, W.D. and Jones, R.T., '
Increased Susceptibility to Memory Intrusions and the Stroop Interference Effect
During Acute Marijuana Intoxication,' Psychopharmacology 91: 20-24 (1987)
Claim C: Use of marijuana does not cause difficulties in learning.
1.Grounds: No evidence found that marijuana users suffer from brain
impairment.
2. Warrant: Since there is no evidence correlating marijuana use to
brain impairment there can be no learning difficulties associated specifically
with the use of marijuana.
3. Backing: A study in 1988 shows ' In comparing chronic marijuana
users with non-users, there are no significant differences in learning, memory
recall, and other attention functions.'(6) Page, J.B., 'Psychosociocultural
Perspectives on Chronic Cannabis Use: The Costa Rican Follow Up,'Journal of
Psychoactive Drugs 20: pp 57 (1988)

Contention II: Marijuana does not impair immune system functioning.
Claim A: Using marijuana stimulates the immune system.
1. Grounds : In the last two years THC (the active drug in
Marijuana)has been discovered as a ' Peripheral cannabinoid receptor associated
with lymphatic tissue proving as a effective immune system stimulant'(7) Lynn,
A.b. and Herkenham, M., 'Localization of cannabinoid Receptors and Non saturable
High Density Cannabinoid Binding Sites in Peripheral Tissues of the Rat:
Implications for Receptor- Mediated Immune Modulation by Cannabinoids, '
Journal of Pharmacology and Experimental Therapeutics 268:1612-23 (1994)
2. Warrant: The active drug in marijuana is THC, thus marijuana is an
immune stimulant.
3. Backing: In 1988, a study showed ' an increase in responsiveness
when white blood cells from marijuana smokers were exposed to immunological
activators.(8)Wallace, J.M. et al, 'Peripheral Blood Lymphocyte Sub populations
and Mitogen Responsiveness in Tobacco and Marijuana Smokers,' Journal of
Psychoactive Drugs 20: 9-14 (1988)
Claim B: Use of marijuana does not increase bacterial, viral or
parasitic infection.
1.Grounds: There has never been any scientific data which proves
marijuana increases bacterial, parasitic or viral infections among humans.
2.Warrant: Since there is no evidence of an increase in viral,
parasitic or bacterial infection when marijuana ...