Fifty terms you will meet in a commercial vehicle injury claim, defined in plain English and grouped by where you will run into them. Adjusters, doctors, and lawyers all use words that sound ordinary but carry precise meanings, and misreading one can cost you a claim. Every term links directly, so you can send someone straight to the definition you mean.
By Michael Mangione, Legal Research EditorLast reviewed August 1, 202614 min read
50 terms defined Plain English, no circular definitions Every term individually linkable State variations flagged Reviewed and dated Not a law firm 50 terms defined Plain English, no circular definitions Every term individually linkable State variations flagged Reviewed and dated Not a law firm
Terms defined
50, in five groups
Trucking rules, fault, injury and medical, insurance and money, and court procedure.
Most misunderstood
Release and MMI
One permanently closes your claim. The other decides when it is safe to value it.
Most valuable
Spoliation letter
The document that tells a carrier to stop deleting the evidence in your case.
Watch for
State variation
Several of these terms are defined differently by state statute. Those are flagged where it matters.
Key takeaways
Ordinary words carry precise legal meanings. Negligence, damages, release, and discovery all mean something narrower in a claim than they do in conversation, and the narrow meaning is the one that binds you.
Some definitions change at the state line. Comparative negligence, wrongful death standing, and damages caps are creatures of state law. Where a term varies materially, this glossary says so instead of picking one version.
Two terms deserve extra attention. A release ends your claim permanently, including for treatment you have not had yet. Maximum medical improvement is the point at which anyone can sensibly value what you lost.
Knowing the words is not the same as knowing your claim. This page will help you follow a conversation and ask sharper questions. It will not tell you what your facts mean, which is what an attorney is for.
Definitions, not advice
These are general explanations written for people trying to follow their own case. They are not legal advice, they are not exhaustive, and reading them creates no attorney-client relationship. Legal terms take their operative meaning from the statutes and decisions of a particular state, which can differ from the general description given here. Nothing on this page guarantees or predicts any outcome. If you are facing a medical emergency, call 911.
01 Trucking and federal regulation
Quick answer
Commercial trucking is governed by a federal rulebook that has no equivalent in ordinary car crashes. These terms describe the companies, the paperwork, and the electronic records that decide whether a safety violation can be proven.
Motor carrier
The company that operates commercial vehicles to transport goods or passengers. The carrier holds the operating authority the truck runs under and is usually responsible for the driver's conduct, hiring, training, and vehicle maintenance.
FMCSA
The Federal Motor Carrier Safety Administration, the agency within the US Department of Transportation that writes and enforces the safety rules for interstate commercial vehicles.
FMCSR
The Federal Motor Carrier Safety Regulations, found at 49 CFR Parts 350 to 399. This is the rulebook covering driver qualification, hours of service, vehicle inspection, maintenance, drug and alcohol testing, and insurance minimums.
Hours of service
The federal limits on how long a driver may drive and remain on duty before rest is required, set out at 49 CFR 395.3. Violations are among the most common causes of fatigue related crashes and among the most provable.
Records of duty status
The driver's log of driving, on duty, off duty, and sleeper berth time. Under 49 CFR 395.8(k)(1) a carrier must keep these and their supporting documents for six months from receipt, which is a retention minimum rather than a preservation guarantee.
Electronic logging device
The hardware, usually shortened to ELD, that automatically records driving time by connecting to the vehicle's engine. It replaced paper logs for most drivers and is far harder to falsify, which is why its data matters so much.
Telematics
The broader stream of electronic data a modern truck generates, including GPS position, speed, braking, engine fault codes, and sometimes video. Much of it overwrites on a rolling cycle, which is why preservation demands need to go out early.
Freight broker
A company that arranges transportation between a shipper and a motor carrier without carrying the goods itself. A broker that selects an unsafe carrier can face a negligent hiring claim, an issue the Supreme Court resolved in 2026.
Bill of lading
The document issued when freight is accepted for transport. It identifies the shipper, the carrier, and the cargo, and it is often the fastest way to work out which companies were actually involved in a load.
USDOT number
The identifier a carrier must display on its vehicles. It unlocks the carrier's public safety record, including inspections, violations, and crash history, and it is usually the first thing to photograph at a scene.
Regulation
The six month floor that decides whether a violation can be proved
49 CFR 395.8(k)(1)
A motor carrier must retain a driver's records of duty status and supporting documents for six months from receipt. Because that is a minimum retention period and not a preservation duty, the practical question in most cases is whether someone demanded preservation before the clock ran out.
Fault has a vocabulary. These are the words that carry it.
02 Fault and liability
Quick answer
Liability is not simply a question of who made the mistake. These terms describe how responsibility is proved, how it is shared, and how it can extend from the driver to the companies behind them.
Negligence
The failure to use reasonable care in the circumstances. Proving it generally requires four elements: a duty owed to you, a breach of that duty, a causal link between the breach and the harm, and actual damages.
Duty of care
The legal obligation to act with the caution a reasonable person would use. Commercial drivers and carriers are held to the standards in the federal safety regulations as well as ordinary care.
Negligence per se
A doctrine under which violating a safety statute or regulation designed to protect people like you is treated as negligence in itself, rather than merely as evidence of it. Hours of service violations are a common example.
Proximate cause
The requirement that the harm be a sufficiently close and foreseeable consequence of the breach. A defendant is not liable for every result that would not have happened but for their conduct, only for those the law treats as legally connected.
Vicarious liability
Responsibility placed on one party for the acts of another because of the relationship between them, most often an employer for an employee acting within the scope of their work.
Respondeat superior
The Latin name for the employer form of vicarious liability. It is what allows a claim against a trucking company for a driver's conduct without proving the company itself did anything wrong.
Negligent hiring
A direct claim against a company for entrusting work to someone it should have known was unfit, based on the company's own failure rather than the employee's. In trucking it can reach the carrier and, since 2026, the freight broker.
Comparative negligence
The rule that reduces a recovery by the claimant's own share of fault. States differ sharply: some allow recovery whatever the share, others bar it once the share crosses a threshold. Your state's version controls.
Contributory negligence
A far harsher rule, retained by only a small number of jurisdictions, under which any fault on the claimant's part can bar recovery entirely. Where it applies, apportioning blame becomes the whole case.
Joint and several liability
A rule allowing a claimant to recover the full amount from any one of several responsible defendants, leaving those defendants to sort out contributions among themselves. Many states have limited or abolished it.
Landmark case
Negligent hiring reaches freight brokers
Montgomery v. Caribe Transport II, LLC, No. 24-1238, 608 U.S. ___ (May 14, 2026)
A unanimous Supreme Court held that a state law negligent hiring claim against a freight broker falls within the FAAAA safety exception at 49 U.S.C. 14501(c)(2)(A) and is not preempted, because requiring a broker to use ordinary care in choosing a carrier concerns the motor vehicles carrying the goods. The Court expressly left open how the analysis applies to purely intrastate loads. Read the opinion
These are the clinical terms that appear in records and reports and that carry weight in valuing a claim. They are explained here for legal context. None of this is medical advice.
Traumatic brain injury
An injury to brain function caused by external force. Severity ranges from concussion through severe, and consequences for memory, mood, and executive function can persist long after imaging looks normal.
Diffuse axonal injury
Widespread tearing of nerve fibres caused by rotational forces, common in high speed collisions. It is often invisible on standard CT imaging, which is one reason serious brain injuries are sometimes missed early.
Glasgow Coma Scale
A clinical score from 3 to 15 recording eye, verbal, and motor response, used to grade the initial severity of a brain injury. It appears in nearly every emergency record and is frequently referenced in claims.
Post-concussive syndrome
Persisting symptoms after a concussion, such as headache, fatigue, light sensitivity, and difficulty concentrating. Because the symptoms are subjective, documentation over time carries more weight than any single visit.
Spinal cord injury
Damage to the spinal cord that disrupts signals below the level of injury. Vehicle crashes are among the leading reported causes, and consequences depend heavily on the level and completeness of the injury.
Complete and incomplete injury
A complete spinal cord injury leaves no motor or sensory function below the level of injury. An incomplete injury preserves some function, and the distinction drives both prognosis and the cost of future care.
Paraplegia and tetraplegia
Paraplegia affects the lower body and legs. Tetraplegia, also called quadriplegia, affects all four limbs and results from injury higher in the spinal column, with correspondingly greater care requirements.
Maximum medical improvement
The point at which a condition has stabilised and further substantial recovery is not expected. It matters because valuing a claim before this point risks settling for less than the injury will actually cost.
Permanent impairment rating
A physician's percentage assessment of lasting functional loss, often expressed for a body part or the whole person. It is one input into damages, not a formula that produces a settlement figure.
Life care plan
A costed projection of the future medical care, equipment, therapy, and assistance a catastrophically injured person will need. In severe cases it is frequently the single largest component of a claim.
Why maximum medical improvement matters more than it sounds
An offer that arrives before your treating physicians can say whether the injury is permanent is an offer made without the most important fact. Accepting it means signing a release, which closes the claim for good, including for surgery, therapy, and complications nobody had identified yet. Timing is not a technicality here.
Following the money
Coverage, liens, and fees decide what actually reaches you.
04 Insurance and money
Quick answer
A claim is worth what can actually be collected, not what a jury might theoretically award. These terms describe where the money comes from, who has a call on it, and what reaches you at the end.
Policy limits
The maximum an insurer will pay under a policy. In catastrophic cases the limits, rather than the severity of the injury, frequently determine what a claim can recover.
Financial responsibility minimum
The lowest level of insurance a carrier must maintain. Under 49 CFR 387.9 most for-hire interstate carriers of non-hazardous property must carry at least $750,000, a figure set in 1980 and never indexed for inflation.
Excess and umbrella coverage
Additional layers of insurance sitting above a primary policy, triggered once the layer beneath is exhausted. Finding these layers is often the difference between a partial and a full recovery.
Uninsured and underinsured motorist coverage
Coverage on your own policy that pays when the at fault party has no insurance or not enough. Many people do not realise it can apply to a crash with a commercial vehicle.
Subrogation
An insurer's right to step into your shoes and recover what it paid from the party at fault. In practice it usually shows up as a claim against your settlement rather than a separate case.
Lien
A legal claim on your recovery held by someone who paid for your treatment, such as a health insurer, a hospital, Medicare, or Medicaid. Liens are frequently negotiable, and reducing them directly increases what you keep.
Medicare set-aside
Funds allocated from a settlement to cover future injury related treatment that Medicare would otherwise pay. Where required, getting the allocation wrong can jeopardise future benefits.
Contingency fee
A fee arrangement under which the attorney is paid a percentage of the recovery and nothing if there is no recovery. In serious injury work this commonly runs from 33 to 40 percent and often steps up if suit is filed.
Case costs
The expenses of running the case, separate from the fee, including filing fees, records, depositions, and expert witnesses. Whether you owe these if the case is lost depends entirely on your written fee agreement.
Bad faith
An insurer's unreasonable handling of a claim, such as refusing to settle within limits when liability is clear. Where it applies, it can expose an insurer beyond the policy limits, though the standard varies by state.
These are the terms that describe how a claim moves, and the two or three that can end it whether or not you meant them to. The deadline terms are the ones to read twice.
Statute of limitations
The deadline for filing suit, set by each state. Injury claims commonly fall in a two to four year window measured from the crash, and missing it generally ends the claim regardless of its merit.
Notice of claim
A formal written notice that many states require before suing a government entity, often due within months rather than years. Missing it can bar a claim even when the ordinary limitations period has years remaining.
Tolling
The pausing of a limitations period in defined circumstances, such as where the claimant was a minor or legally incapacitated. It is a doctrine a court applies to particular facts, never something to plan around.
Spoliation
The destruction or loss of evidence a party had a duty to preserve. Where it is established, courts can impose sanctions, including instructing a jury to assume the missing evidence was unfavourable.
Preservation letter
A demand, sometimes called a spoliation or legal hold letter, requiring a carrier to preserve logs, telematics, video, and maintenance records. Sending it early is often the highest value step in a trucking case.
Demand letter
A written statement of the claim and the amount sought, usually sent with supporting records once treatment has stabilised. It typically opens formal settlement negotiations.
Discovery
The court supervised exchange of information before trial, including written questions, document production, and depositions. It is where the carrier's internal records usually surface.
Deposition
Sworn testimony taken out of court, recorded by a court reporter, in which the other side's attorney questions a witness directly. Testimony given here can be used at trial.
Release
The document signed to conclude a settlement. It permanently ends the claim, normally including for future treatment and complications, which is why it should never be signed without independent review.
Mediation
A negotiation run by a neutral third party who has no power to impose a result. Most injury claims resolve through negotiation or mediation rather than at trial.
Two terms that end claims
A statute of limitations ends a claim by time. A release ends it by signature. Neither can usually be undone. Everything else in this glossary describes a process you can still influence. These two describe doors that close.
If a term here has made you realise something in your own paperwork means more than you thought, that is the point at which general information stops being enough. A licensed attorney can tell you what it means for your facts, and comparing attorney qualifications is covered in our guide to choosing a truck accident lawyer.
Questions about using this glossary
General information about terminology, not legal advice, and no attorney-client relationship is created by reading it. For what a term means in your own case, talk to a licensed attorney.
Why do lawyers and adjusters use different words for the same thing?
Often because they are not describing quite the same thing. An adjuster may say your claim is worth a figure, meaning what they are authorised to pay today. An attorney saying the same words may mean what a jury could award after full workup. Vocabulary also does persuasive work: a settlement described as final and generous is still a release, and the operative word is release.
If a definition here conflicts with my state's law, which one applies?
Your state's, always. These definitions describe how terms are generally understood across US injury practice, but legal terms take their operative meaning from the statutes and decided cases of a particular jurisdiction. Comparative negligence, wrongful death standing, damages caps, and joint and several liability all vary materially by state. Where that variation matters, this glossary flags it rather than presenting one state's rule as universal.
Does understanding these terms mean I can negotiate my own claim?
It means you can follow the conversation, which is worth having. It does not close the gap that matters. The other side knows what your claim is worth because they have the data, the medical expertise, and the experience of thousands of similar files. Knowing the vocabulary helps you ask better questions and spot when something is off. It does not give you the leverage that comes from being able to file suit and try the case.
Which term on this page causes the most damage when it is misunderstood?
Release, without much competition. People sign one believing it settles the medical bills they have already received, and discover later that it closed the claim for everything, including surgery they had not been told they would need. It is a short document with permanent effect. Nothing else on this page is as final except a missed filing deadline.
Why does this glossary refuse to give formulas for calculating damages?
Because the formulas circulating online do not reflect how claims are actually valued. Multiplying medical bills by a number is not a method any insurer or court uses, and an impairment rating is one input among many rather than a conversion rate. Publishing a formula would give false precision about the single question people most want answered, so we explain the inputs instead.
How do I link someone directly to one of these definitions?
Every term on this page has its own anchor. Click a term heading and your browser address bar will show a link ending in the term's name, which you can copy and send. That is deliberate: it lets you point a family member, or a professional you are working with, at exactly the definition you mean rather than at the whole page.
Is a term missing from this list?
Very likely, since fifty terms cannot cover a field this large. We prioritised the words that appear in ordinary correspondence with adjusters and in the first conversations with an attorney, plus the trucking specific vocabulary that has no equivalent in a car crash. If a term you keep encountering is not here, tell us and we will consider adding it, since the gaps readers report are better signal than our own guesses.
Are these definitions the same as legal dictionary definitions?
They are written to be understood rather than to be technically exhaustive. A legal dictionary aims at precision for lawyers, including exceptions and historical usage. This glossary aims at a person trying to follow their own case, so it gives the working meaning and flags where states diverge. For the operative definition in litigation, the controlling statute or decision governs, not any dictionary.
Sources and authorities
The regulations and decisions behind the defined terms are listed below, each linked to a free public database so you can check any definition against the original text.
Federal regulations
Federal Motor Carrier Safety Regulations, 49 CFR Parts 350 to 399. FMCSA.
Every definition on this page is held to the same standards as the rest of the site.
01
Primary sources only
Legal claims cite the statute, regulation, or decided case itself, never another firm's summary of it, and the link opens the original text.
02
Reviewed and dated
A named editor signs off on every page, the review date is printed on it, and the page is re-checked when the law changes.
03
Editorial, not legal advice
This is general information to help you make decisions, not advice about your specific case, and it creates no attorney-client relationship.
04
Honest about how we operate
We are an independent referral service, not a law firm, and we may be paid if you hire a lawyer through us. That is disclosed, and it buys no coverage.
Michael Mangione Verified editor
Legal Research Editor · Founder, The Mangione Group, Inc.
This glossary was assembled by Michael Mangione, who has spent more than twelve years working alongside contingency based law firms across the United States, sitting inside their intake departments and listening to how people describe what has happened to them. The terms collected here are the ones that most often caused confusion in that first conversation, defined the way he found himself explaining them. Michael is not a practicing attorney and does not give legal advice.
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