Okay, thanks. That's helpful, because I'm a California lawyer!
California courts observe a doctrine described as "pure comparative negligence." This means that the judge or jury must determine the percentage of negligence that is attributed to both the plaintiff and the defendant. For example, if the defendant is determined to be 25% negligent, then the plaintiff can only recover 75% of the damages requested. If defendant is 50% negligent, and plaintiff is 50% negligent, then plaintiff is entitled to 50% of the damages requested.
But, if both plaintiff and defendant sue each other for negligence, then no matter what the outcome, neither party can collect against the other, because every result is a "wash." One party's recovery will always be exactly equal to that same party's damages. Only in the situation where one party fails to prove any negligence against the other would that party become liable -- in which case, the result would be 100% liability.
Definitely not a simply concept, but that's how it would work, given the circumstances you describe.
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