Resolved: The abuse of illegal drugs ought to be treated as a matter of public health, not of criminal justice.The following list--a work in progress--should be taken as a set of suggestions. You might have better ideas, and you know what you know, and what you'll need to research. If you have any brilliant ideas or questions, feel free to share in the comments.
I've separated the pairs into three groups.
V: Justice (defined as "to each their due," or a similar concept)
Some varieties of retributivism match well with the Affirmative argument that drug abuse itself is not a crime, and hence punishing it is as such is immoral. For the dissenting view--that drug abuse could represent a violation of "equal liberty for all," and its punishment justified on retributivist grounds--see here.
V: Liberty or Autonomy
C: Mill's Harm Principle
Liberty is the basis of human rights and flourishing. Its close cousin, autonomy, precedes any sort of societal or law-and-order consideration, because it is the foundation of human rights and societal order. If the Aff can show that drug abuse is a separate moral matter from drug manufacture or trafficking, then people have a right to hurt themselves through drug abuse. (If they hurt others, we already have justification enough for punishment.)
V: Health or Societal Welfare
C: Paternalism (via Utilitarianism)
One Aff strategy will be to declare that drug abuse is a "victimless crime." To a paternalist, this is irrelevant; the state has a responsibility to keep folks from harming themselves. (A utilitarian justification exists: one's suffering, or even lack of productivity, inevitably affects society.) The danger, of course, is a slippery slope to tyranny. A paternal state is seldom satisfied with the limits of its power.
V: Societal Welfare
C: Upholding Moral Standards
Morality is good because it holds society together. (There may be social contract implications lurking beneath the surface of this structure.) If the core value of a society, then we are justified in punishing those who commit offenses against morality.
Strategy for Success: This criterion respects differences across societies, since the resolution doesn't specify any particular society. However, it also leaves one open to the attack that morality is difficult to define and agree upon, even within a society.
Could Go Either Way
V: Societal Welfare
The utilitarian theory of criminal justice is based on the beneficial outcomes of punishment: preventing future crimes through deterrence, incapacitation, and rehabilitation. However, in the wider context of utilitarianism, punishment is counterproductive if its costs outweigh the benefits. Any statistical argument about treatment outcomes or deterrence is most likely utilitarian in nature.
Strategy for Success: Be sure to show how Util leads to SW. Watch out for the "50.01% can kill 49.99%" response, an oversimplification of Utilitarianism. Learn about the nuances and varieties of the moral philosophy. They're worth exploring.
V: Human Rights / Justice
C: International Law / International Human Rights Norms
Since the resolution does not specify a particular society, we can't be 100% certain which rights must be protected. Best, then, to look to the prevailing standards of international law--the rights that people across societies, cultures, and even times have agreed are essential. Is this criterion open to attack? Certainly. But it also presents a clear, highly defensible set of rights (and jurisprudence as evidence). It's worth looking into the international perspective on drug offenses, and whether it supports a public health or a mixed approach.
C: Rawls' first principle of justice (or, more generally, the Rawlsian social contract)
C: Equal protection of the laws
V: Human Rights
C: Locke's Social Contract
V: The General Will
C: Rousseau's Social Contract
V: Justice (defined in terms of morality)
C: The Categorical Imperative
According to Kant, moral actions are good in and of themselves. Furthermore, Kantian theory applies to all rational agents--criminals and law enforcers alike. Those who punish criminals are bound by moral obligation to punish them to the fullest.
Strategy for Success: Many people misunderstand Kant and the Categorical Imperative, so make sure you do the research first.
V: Justice / Societal Welfare
C: The Rule of Law
The Aff could argue that criminalizing drug abuse leads to a War on Drugs, that dehumanizes drug abusers, empowers criminals, sets children against parents and parents against children. This diminishes respect for the law, which is the closest approximation to real justice in a given society. Further, diminishing the rule of law has wider social consequences. (Or, on the Negative, would decriminalizing drugs via a public health approach do the same? Do we risk a slippery slope to drug-fueled, soporific anarchy?)