First of all, I was in no way comparing dope smokers to heroes. I was citing an obvious example in which the law was clearly wrong, and those who broke it were obviously right. They (both escaped slaves and those who sheltered them) were regarded in some circles as criminals and "scofflaws", but it was in that case clearly the right thing to do, despite being unlawful.
I make no such assertion regarding dope smokers. Their habit, in most cases, is what we would characterize as a vice (were it legal and not done to excess), similar to smoking tobacco (nicotine being a powerfully addictive and dangerous drug) or drinking alcohol (another powerful and dangerous drug) in moderation. In some situations, marijuana and cocaine (and wine or beer) are at least alleged to be therapeutic, and many doctors agree.
But vices are not inherently criminal. In general, we prefer to discourage vices rather than criminalizing them, and in the case of alcohol, we forbid certain activities like driving or handling firearms while under the influence. ("Avoid strong drink", goes the saying, "it can make you shoot at revenooers, and miss!")
The purpose of the law is to maximize peaceful cooperation while minimizing the overall levels of coercion. Hence, the coercion required to minimize violent crimes like murder, rape, robbery or assault is justified because it decreases the overall level of coercion and violence in our society, while redressing real harm done to real victims. Traffic regulations also serve to maximize peaceful cooperation by providing each of us with a reliable expectation of everyone else's behavior on our roads. We easily avoid conflict on our roads because, by and large, we honor those rules and they do not often change, so our expectations are realistic.
With drug prohibition, this is not the case. Demand for these substances is persistent and elastic with regard to cost. Enforcement is problematic, interdiction difficult and fiercely resisted. The cost of enforcement is enormous, and realization of the continuing failure of their efforts has prompted law enforcement to seek ever more intrusive powers by which to seek out and arrest those engaging in the black market trade. The result has been an incremental loss of freedom, even for those of us who have no connection to the drug trade at all.
The efforts continue to fail: each year we hear stories of new interdictions of record-breaking quantities of MJ or cocaine or crack or heroin, but these anecdotes only serve to illuminate the failure of interdiction as a strategy. The dollar value of the drug market, by best estimates, continues to increase. The record confiscations are only minor setbacks to the smugglers.
The point, which we seem not to have learned from our experience with alcohol prohibition, is that vice is not crime. Yes, those who engage in their chosen vices often injure themselves and occasionally injure others, but only in the latter circumstance does it make sense to involve law enforcement. So we ignore the vice of smoking, except to tax it and propagandize against it, and we ignore the vice of drinking, except to tax it and propagandize against it, except in those cases where someone who is intoxicated drives poorly enough to be noticed for creating a hazard to or injuring others. Creating the hazard is sanctioned, and causing injury is punished criminally, as it should be.
Regardless of the relevance (or lack thereof) of the LP as a political force, many or most of their principled positions are sound and well considered. Saying that "the LP is irrelevant so we don't have to listen to them" is a rather childish approach to rational discourse, don't you think?