The nation is torn. Currently, marijuana's legal status in the schedule 1 classification presents it as a dangerous drug, that is highly addictive and has no medical value. The truth is that with the vast majority of studies that have been done, marijuana is shown to be significantly safer than current recreational drugs like cigarettes and alcohol. In fact marijuana in it's over 10,000 years of use has had zero related deaths. Unfortunately, even though a vast majority of groups agree that marijuana should be decriminalized, it seems that when ever a bill is put through Congress or Senate it is quickly dismissed and never again heard of. The rescheduling and decriminalization of marijuana has been making some headway through out the years. 14 states as well as DC have approved marijuana for medical use, and 10 have decriminalized possession of a small amount making it punishable by only a small fine. Currently, in California, there is a proposition to legalize, tax, and regulate the plant for recreational and commercial use.
So either way in any state is currently illegal to smoke marijuana. That doesn't stop the 42% of people in the United States from trying it and the 16% of those who smoke it regularly, like myself. So when handed a marijuana cigarette, what should you do? Well, you can either take a puff or two and see that it isn't as harmful as many government funded organizations like to portray, or you can just take their word for it. (Not the best suggestion in any case, if you want my opinion.).
 Source: Iversen, Leslie L., PhD, FRS, "The Science of Marijuana" (London, England: Oxford University Press, 2000), p. 178, citing House of Lords, Select Committee on Science and Technology, "Cannabis -- The Scientific and Medical Evidence" (London, England: The Stationery Office, Parliament, 1998).