Death penalty for drug dealing is quite extreme. I go back and forth on capital punishment anyway, but whenever I'm in a supportive mood, it's only for certain things. Drug dealing isn't one of them, because... what drugs are we talking about?
One problem is that the propaganda smear campaigns of the 80s and 90s colored all recreational drugs (except caffeine, alcohol, and tobacco, apparently) as horrible evil devil-spawn, and all drug dealers as minions of Satan who are just out to get kids on drugs because EVIL!!!! While this probably did help keep kids off recreational drugs, which is certainly a good thing, it didn't do well for real education on what, exactly, is what when it comes to drugs. Not all of them are addictive or damaging, for one thing, and many have positive qualities similar to caffeine. Sure, too much will kill you, but the same is true of everything. I drink caffeine all the time, and if I had too much in too short of time, I'd most certainly die. But that's no reason to make it illegal. There's also the fact that drugs are also used frequently in medicine; I'm on a carefully-dosed prescribed amphetamine, for instance, because it helps me stay focused, productive, and in good spirits. It's for that reason that when referring to these types of drugs, I specify recreational drugs.
Now, I'm fully in favor of certain recreational drugs being illegal, particularly crack and heroin. These are highly addictive and highly fatal, with any "benefit" effectively rendered null by the negative effects. Pot, however, is harmless in itself (though inhaling smoke is never a good idea no matter what's on fire), and other recreational drugs like LSD are so restricted that proper research to determine their exact effects is incredibly difficult to do, which means they're illegal out of generalized fear rather than certainty. (Though I'm not sure I'd want LSD to be legalized for recreational use, since it's an hallucinogen, but if other effects are what I hear tell, it might be an effective medicine in VERY controlled doses, and I believe it should be fully legal for certain shamanic contexts).
But death by firing squad for selling drugs? Drug dealers aren't necessarily as the propaganda depicted: often they're just people like anyone else trying to feed themselves and their families like everyone else. The negative effects are certainly bad enough to warrant jail time, but not death.