Legal Terms, Defined and Sourced

Autonomous vehicle and driver-assist liability

Most states have no full law on liability when a car's computer, not a person, is driving. Courts often use existing negligence and product rules instead. They ask who was really at fault: the driver, the maker, or the software. A few states have added narrow rules that mention self-driving cars, but none has passed a full liability law yet.

Also under Accident & Liability Laws

Bicycle laws

Most states require cyclists to ride near the right side of the road, with exceptions for hazards or turns. These laws also say whether a cyclist can use a full lane or ride on a sidewalk. A driver who does not give a cyclist enough space often causes these crashes.

Commercial vehicle and trucking laws

The Federal Motor Carrier Safety Administration sets a nationwide floor for driving hours and licensing. Federal rules also cap truck weights, enforced separately by the Federal Highway Administration. States can add rules on top of these floors. A trucking company that lets a driver break these rules can share the blame for a crash.

Distracted driving

Most states ban texting or handheld phone use while driving. Some states ban any phone use for new drivers. Distraction slows reaction time much like impairment does, and shows up often in crash reports.

Dram shop and social-host liability

Many states hold a bar or restaurant liable for serving an obviously intoxicated or underage customer who then causes a crash. Fewer states extend that liability to a social host who overserves a guest at a private party. A few states don't allow this kind of claim at all.

E-scooter and micromobility laws

These newer laws cover where a scooter may be ridden and whether a helmet is required. They also address liability between a rider, a pedestrian, and the scooter company. Coverage is uneven and still developing state by state.

Following distance

States require drivers to leave enough room to stop safely, often described as a reasonable distance rather than an exact number. Following too closely, or tailgating, causes many rear-end crashes. The exact rule varies by state.

Hit-and-run and duty to remain

Leaving the scene of a crash, especially one with an injury, is a hit-and-run and usually a crime. Most states require a driver to stop, share information, and call for help if someone is hurt. If the fleeing driver is never found, the injured person may still have coverage through their own uninsured-motorist policy.

Impaired driving

Every state sets a blood alcohol limit, usually 0.08%, above which a driver is presumed impaired. Holding a license means agreeing to a chemical test if stopped, under implied consent laws. An impaired driver who causes a crash often faces criminal charges too.

Lane laws

These rules set when a driver may change lanes or pass, and where passing is banned, like on a solid line. Some states also regulate lane splitting, where a motorcycle rides between slow lanes of traffic. Lane rules vary by state.

Motorcycle laws

States differ widely on helmet laws, from requiring helmets for every rider, to only young riders, to a few states with no helmet requirement at all. These laws also cover how a rider may position their bike within a lane. Because riders have little protection, these rules matter a great deal after a crash.

Pedestrian laws

A pedestrian in a crosswalk, marked or unmarked, generally has the right-of-way. Drivers must yield and use caution around pedestrians even outside a crosswalk. Exact crosswalk rules vary by state. Jaywalking can affect fault, but a jaywalking pedestrian can often still recover damages.

Reckless and aggressive driving

This covers behavior like extreme speeding, weaving through traffic, or ignoring traffic signals in a dangerous way. It's usually a criminal charge on top of any traffic ticket. It can also support a claim for punitive damages in an injury case.

Right-of-way

Right-of-way rules tell drivers, cyclists, and walkers who must yield so an intersection stays safe. Every state writes its own version, though most agree on the basics, like yielding to whoever entered first. Breaking a right-of-way rule is a common reason a driver gets blamed for a crash.

Seatbelt and child-restraint laws

Nearly every state requires seatbelts for front-seat adults. New Hampshire is the only state that doesn't require adult seatbelt use. All states require car seats or booster seats for young children based on age or size. These laws reduce injury severity; they don't decide who caused a crash.

Also under Injury & Recovery Laws

Signal and stopping laws

These laws set when a driver must fully stop, including before turning right on red. Running a red light or a stop sign is a clear way to be found at fault for a crash. Right-on-red rules vary by state and intersection.

Speed laws

Every state posts a numeric speed limit. Most states also ban driving too fast for conditions like rain or heavy traffic, even under that limit. Speeding cuts a driver's reaction time and makes a crash more severe.

Comparative negligence

Pure comparative fault lets a person recover something, even at 99% fault. Modified comparative fault cuts off recovery once a person passes a 50% or 51% fault line. In a pure-comparative-fault state, a person's own fault reduces a recovery but never wipes it out.

Also under Injury & Recovery Laws

Contributory negligence

Under this rule, being just 1% at fault can wipe out an entire claim. Only a few states still use it. Most states have moved away from it and use some form of comparative fault instead, where a person's own fault reduces recovery rather than barring it.

Also under Defenses

Damages

Compensatory damages cover real losses. Economic damages include medical bills and lost wages. Non-economic damages cover pain and lost enjoyment of life. Punitive damages are rarer, meant to punish reckless conduct, not to pay the injured person back.

Also under Injury & Recovery Laws

Damages caps

Many states cap non-economic damages, especially in malpractice cases. A few states bar these caps entirely for death or injury claims, sometimes with a narrow exception for someone hurt while committing a crime. Caps vary so much that a similar injury can be worth very different amounts by state.

Also under Injury & Recovery Laws

Discovery rule

Some injuries are not obvious right away, like a slow illness or a delayed symptom. Courts let the filing clock start later, once the injury is discovered. In many states, courts created this rule through case law. In other states, lawmakers wrote it directly into the statute of limitations.

Dog bite and animal liability

Some states hold an owner responsible for any bite, regardless of the dog's history. Others use a one-bite rule, requiring proof the owner knew the dog was dangerous. Local leash laws can also affect a claim, and rules vary by state.

Governmental immunity and notice of claim

Suing a city, county, or state agency comes with extra hurdles a private lawsuit does not have. Many states give only a matter of months to sue a public entity, and require formal notice well before that deadline. Missing these tight deadlines is a common way a valid claim gets lost.

Also under Defenses

Joint-and-several vs. several liability

Under joint-and-several liability, an injured person can collect a full judgment from one defendant, even if others share the blame. Several liability limits each defendant to paying only their own share of fault. Which rule applies depends on your state: some states let you collect a full judgment from one defendant, while others make each defendant pay only their own share. This matters most when one defendant cannot pay.

Negligence

A negligence claim needs four things: a duty of care, a breach of that duty, harm caused by the breach, and real damages. Negligence is the legal foundation under almost every crash and injury claim. These elements come from longstanding common law in nearly every state; Louisiana's civil-law system codifies the same idea in its own statutes.

Negligence per se

An injured person can point to a specific law the other driver broke, like running a red light. In many states, that counts as proof of negligence; in others it's only evidence of negligence, weighed with everything else. Either way, the person still must show the violation caused the injury. It's a common-law doctrine used nationwide, most often tied to a broken traffic law.

Also under Traffic Laws

Negligent entrustment, hiring, and supervision

This differs from vicarious liability. It targets the employer's own carelessness, like hiring a driver with a known history of DUIs. It comes up often in trucking cases, where hiring and training get scrutinized after a crash. Courts nationwide recognize this as its own claim, though details vary by state.

Premises liability

In many states, the duty an owner owes depends on the visitor's status: a customer, called an invitee, usually gets the most care, a social guest gets less, and a trespasser gets the least. Other states use one reasonable-care standard for all visitors, regardless of status. A slip-and-fall from a wet floor is a common example, and the rules vary by state.

Product liability

A product can be defective in three ways: a design flaw, a manufacturing error, or a failure to warn of a known risk. Many states use strict liability, so an injured person only has to prove the product was defective, not that anyone was careless. The exact rules vary by state.

Res ipsa loquitur

This Latin phrase means "the thing speaks for itself." It applies when an accident normally would not happen without someone's carelessness, like a tool left inside a surgery patient. Courts nationwide recognize this rule, though they apply it narrowly.

Spoliation of evidence

A business or driver may lose evidence, like security footage, after knowing a lawsuit was likely. Courts can penalize them for that. Penalties range from an unfavorable jury instruction to striking a defense entirely. These rules come mostly from court procedure, and vary by state.

Statute of limitations

Missing this deadline almost always means losing the right to sue. Most states give two to three years for a personal injury claim, counted from the date of injury. The exact deadline and its start date vary by state and claim type.

Also under Defenses

Statute of repose

Unlike a statute of limitations, this deadline keeps running even if the injury is not yet known. It cuts off a claim completely once it expires. These deadlines show up most in product and construction-defect cases, and vary by state.

Survival action

This differs from wrongful death, which belongs to surviving family members for their own losses. A survival action continues the injured person's own claim, like pain or medical bills, through their estate. Many states allow both claims at once.

Vicarious liability

This rule, called respondeat superior, lets an injured person sue the employer directly, which matters because employers usually carry more insurance. It applies when the employee was acting within the scope of their job, like a delivery driver in a crash. This common-law rule applies the same way across states.

Wrongful death

Every state allows this claim, but each sets its own list of who may bring it, usually a spouse, children, or parents. A common order is spouse, then children, then parents or a guardian, then the estate if no one else survives. The claim compensates survivors for their own losses, separate from the person who died.

At-fault vs. no-fault insurance

In an at-fault state, the driver who caused the crash, or their insurer, pays the other driver's losses. In a no-fault state, each driver's own insurance pays their bills up to a limit, no matter who caused the crash.

Bad-faith insurance

Every insurer owes a duty of good faith. Unreasonably denying a valid claim or refusing to settle within policy limits can expose an insurer to a bad-faith claim on top of the original one. This law comes mostly from court decisions, and standards differ by state.

Collateral-source rule

The at-fault party cannot use outside payment as an excuse to pay less, since the injured person's insurer usually has to be paid back anyway. Some states have limited this rule by statute, especially for medical bills. How strictly a state applies it can change a claim's value.

Damages liens and subrogation

When a health plan pays an injured person's medical bills, it often has a right to be paid back from any settlement, called subrogation. Negotiating these liens down is a routine part of keeping more of a settlement. The rules vary by the type of payer and the state.

Loss of consortium

This claim belongs to the spouse or family member, not the injured person, and covers lost companionship and support. Most states limit it to spouses, though a few extend it to children or parents. Which relationships qualify varies by state.

Medical malpractice

Many states require an early step first: a sworn expert statement backing the claim. Some states pair that requirement with a shorter filing deadline or a damages cap for malpractice cases; others use the same general injury deadline.

Minimum liability limits

These limits are often written as three numbers, like 25/50/15. Each number is a dollar amount: per person, per crash, and for property damage. The required minimums differ by state, and rideshare drivers often must carry higher limits while logged into a driving app.

Also under Traffic Laws

Minor tolling

In most states, the filing clock pauses while the injured person is a child, until they turn 18. Some states limit this pause, especially for medical malpractice claims, so the deadline can still arrive before adulthood. Because a minor cannot file their own lawsuit, this pause gives a parent or guardian more time to decide when to file. Some states add a similar pause for someone found to be of unsound mind.

Minor's compromise and court approval of settlement

Because a child cannot sign off on their own settlement, a parent or guardian must present it to a judge. The judge checks that the deal is fair before approving it. Most states also require notice to everyone else with an interest in the case.

Negligent infliction of emotional distress and bystander recovery

This claim is often called NIED. It usually requires witnessing the injury, being closely related to the injured person, and suffering real emotional harm. It differs from loss of consortium, which covers a different loss. Rules vary widely by state.

Offer of judgment and fee-shifting

If a defendant makes this offer and the injured person wins less at trial, that person may pay some of the defendant's later costs. The reverse can apply to a defendant who unfairly refuses a fair offer. States set the mechanics through court rules, so they vary.

Pre-existing condition and the eggshell-plaintiff rule

A defendant cannot avoid responsibility just because an injured person had a condition that made the crash worse for them. The at-fault party owes for how much the crash worsened or triggered that condition, not the whole condition itself. This rule applies the same way across states.

Prejudgment interest

This interest pays for the delay in getting compensated, since a slow defendant effectively holds money owed to the injured person. The rate and start date vary by state, and some states apply a different, lower rate to medical-debt judgments.

Structured settlements

These are often used in serious injury cases to provide steady income for future care rather than one large payment. The schedule is set by contract and backed by an annuity. Federal tax law gives certain payments favorable treatment, and this structure works the same way nationwide.

Uninsured and underinsured motorist coverage

This coverage is called UM/UIM. It applies when the at-fault driver fled, was never found, or carried too little insurance. Many states require insurers to offer it, though a driver can decline in writing. Minimum limits are often too low, so this coverage can matter as much as the other driver's policy.

Workers' compensation exclusivity

In exchange for guaranteed benefits, most states bar an employee from suing their employer. In most states, the main exception is an employer's intentional harm. If a third party caused the injury, like a negligent driver or a broken machine, the worker can often still sue that party.

Also under Defenses

Assumption of risk

A defendant may raise this when someone chose a risky activity, like a sport, knowing its dangers. In many states this is a jury question folded into comparative fault, rather than an automatic bar to recovery, though how much weight it carries varies by state.

Also under Accident & Liability Laws

Assumption of risk vs. comparative fault interaction

In some states, assumption of risk is a full defense that bars recovery entirely. Other states treat it as one fact for the jury inside the comparative fault analysis instead. This matters a lot, since a full bar and a partial cut give very different results.

Also under Accident & Liability Laws

Failure to mitigate and the seatbelt defense

This defense claims the injured person skipped a reasonable step that would have lessened their injury. Some states let a jury cut damages for this, even though the person did not cause the crash. The seatbelt law itself only requires buckling up. Whether skipping it counts against someone in court is a separate question each state decides.

Also under Injury & Recovery Laws

Last-clear-chance doctrine

This doctrine softened the harsh contributory negligence rule, letting a careless plaintiff still win if the defendant had one last chance to avoid the crash. Most comparative-fault states no longer need it, since fault-sharing already covers this. It still applies in the few states that keep contributory negligence.

Also under Accident & Liability Laws

Non-party-at-fault apportionment

A defendant using this defense usually must give formal notice naming the absent party and their role in the harm. This can shrink what an injured person collects from the named defendants, even though the other person is never sued. Many states allow this with proper pretrial notice.

Also under Accident & Liability Laws

Sudden-emergency doctrine

A driver may react imperfectly to a sudden danger, like a child darting into the road. Courts judge that reaction against what a reasonable person would do in the same moment. This defense usually does not apply if the driver helped cause the emergency. States apply it differently.

Also under Accident & Liability Laws