As with intentional tort, negligence doctrine allows for some defenses. These often focus on the behavior of the plaintiff-victim rather than defendant-wrongdoer. In its more traditional form, to validate a defense was to extinguish all liability: defenses of merit would be complete ones. “Assumption of the risk” is a complete defense to a claim of negligence that says that the victim knowingly and voluntarily undertook the risks arising from the defendant’s behavior (or non-behavior). As the cases invoking it unfolded, there came to be a couple patterns of assumption of the risk. The first might be thought to have the plaintiff’s knowledge of the risk essentially make the defendant’s actions non-negligent to begin with. A steep ski slope properly marked means no liability for the resort not because the plaintiff conceded to risk the resort’s negligence, but because knowledge of the slope’s grade and condition allowed the plaintiff to assess the activity’s inherent risks and knowingly take them on. While that fact pattern might be best described, then, as simply no breach of duty by the defendant, it often outs itself within an assumption of risk defense at all. Another pattern of assumption of the risk is when a defendant’s negligence is acknowledged by the plaintiff and the plaintiff moves ahead nonetheless. Imagine being picked up by a taxi cab that’s manifestly falling apart: a tire is wobbly, and the door almost comes off as you open it. (In Cambridge this does not require much imagination.) If, after that cab responds to your hail, you shrug and get in anyway and the wobbly tire comes off a few minutes later, causing an accident, what result? The cabbie is likely negligent in maintaining the car. But you assumed the risk, and perhaps there should be no liability. Another way to think of this is that you yourself were negligent – breaching a duty owed to yourself to keep yourself safe. That’s contributory (or comparative) negligence, which makes one wonder, then, what’s left for assumption of the risk to do as a doctrine? Good question. As you read today’s cases and tomorrow’s on contributory negligence, it will help to think about how much vitality assumption of the risk retains as a doctrine given what can be folded into either breach in the primary case or into contributory negligence as a separate defense.