Crate comparative_fault 

Apply US comparative-negligence rules to a damages award.

When more than one party is at fault for an injury, the plaintiff’s recovery is reduced by their own share of responsibility. US states do this in four materially different ways, and the same facts can produce very different recoveries depending on which rule applies:

• Pure comparative: recovery is reduced by the plaintiff’s fault share, with no cut-off. A plaintiff 90% at fault still recovers 10%.
• Modified 50% bar: the reduction applies, but recovery is barred once the plaintiff’s share reaches 50%.
• Modified 51% bar: the same, but barred only once the share exceeds 50% (i.e. at 51% or more).
• Contributory negligence: any fault at all bars recovery entirely. Only a small minority of jurisdictions still use this.

The distinction between the two modified rules matters precisely at an even 50/50 split, which is a common settlement posture: under a 50% bar the plaintiff takes nothing, under a 51% bar they take half.

The reference settlement calculator and worked examples are at https://worthmyclaim.com/ — an injury settlement estimator.

Example

use comparative_fault::{net_recovery, Rule};

// 20% at fault on a $100k award, pure comparative: $80k.
assert_eq!(net_recovery(100_000.0, 0.20, Rule::Pure), 80_000.0);

// Exactly 50% at fault: barred under a 50% rule, halved under a 51% rule.
assert_eq!(net_recovery(100_000.0, 0.50, Rule::Modified50), 0.0);
assert_eq!(net_recovery(100_000.0, 0.50, Rule::Modified51), 50_000.0);

Enums

Rule

The comparative-negligence regime applied by a jurisdiction.

Functions

bar_threshold

The fault share at which recovery first becomes zero, if the rule has one.

net_recovery

Net recovery after applying the plaintiff’s fault share under rule.

reduction_amount

The dollar amount lost to the plaintiff’s own fault share.