I (tentatively?) understand that the law of contracts, the law of torts, the law of property, and (probably?) some other areas of law in the U.S.A. are mostly the common law of the separate states.

What are the most prominent differences among systems of common law of the different states in the U.S.A.?

1 Answer 1


I (tentatively?) understand that the law of contracts, the law of torts, the law of property, and (probably?) some other areas of law in the U.S.A. are mostly the common law of the separate states.

With a few exceptions (most prominently Louisiana which have a civil law foundation to its laws that has been influenced for a prolonged time period by its sister common law states, and California which codified much of its common law of torts, contracts, and property), this is true. Most states have some statutory law in these areas, but this is drafted against a foundation of common law rules which these statutes only tweak.

What are the most prominent differences among systems of common law of the different states in the U.S.A.?

I'll list some prominent state to state points of variation in property law, torts, and contracts, largely from memory in an idiosyncratic rather than systemic way. These aren't the only areas of law which are or were historically governed by the common law, but they figure most prominently in the law school curriculum and in civil litigation.

Some of these differences reflect early U.S. history or regional trends. Other differences are more or less random and simply reflect how key precedents were decided when the legal issue first arose in that particular state, or the priorities of particular state legislators not particularly specific to the regional conditions of a state.

Incidentally, a recent study has also found that variation in the substantive rules of criminal law between different U.S. states (which is mostly statutory) is mostly more or less random and does not strongly track the partisan "red" or "blue" leanings of particular U.S. states.

Property Law

Property law tends to be less uniform than contract law or tort law.

  • Some U.S. states have community property regimes for property owned by married people, based mostly on the Spanish system of old Mexico. Other U.S. states have separate property regimes based upon English law with a discretionary equitable division of spouses upon divorce and certain statutory rights at death if a decedent's estate is not generous enough to a surviving spouse (sometimes in the modern "forced share" concept of the Uniform Probate Code, and others adapting the historical notions of dower and curtsy). The American South also has some rather queer laws designed to keep inherited real estate (think plantations) in the family.

  • A few Northeastern states have a form of ownership called "tenancy by entireties" reserved for married couples that can only be seized by judgment debtors who are creditors of both spouses. The homestead exemption for real estate varies greatly, with Texas having an extreme protection for homestead, very stingy homestead exemptions in the Northeast, generous homestead exemptions in the Great Plains and the West, and homestead exemptions and rights at an intermediate level in between. The personal property which is exempt from creditors' claims also varies greatly from state to state.

  • States vary modestly in the extent to which they recognize some of the more obscure common law future estates in real property such as fee tail, fee simple subject to defeasance, fee simple subject to possibility of reverter, etc. Many recognize only life estates and remainder interests following a life estate, and treat attempts to establish other future interests in land as void as a matter of law as an unlawful restraint on the alienation of property.

  • In most of the U.S., when real estate is used as collateral for a debt, this is done with a mortgage. But in much of the Western United States, an instrument known as a "deed of trust" is usually used instead. A deed of trust is nominally a three party instrument, with the borrower nominally conveying the real estate to a third-party trustee for the benefit of the lender, in a structure that was designed to facilitate non-judicial foreclosures.

  • Several states (including California and Florida) have laws that essentially make loans secured by owner occupied residences "non-recourse" which is to say that if the price secured in a foreclosure sale is less than the amount owed on the loan, it is difficult or impossible for the lender to sue to debtor-homeowner for the difference. The overwhelming majority rule, however, if a residence is sold in a foreclosure sale for less than the outstanding balance of the loan, the unpaid portion becomes a deficiency judgment which the lender can enforce against the borrower-homeowner like any other judgment. Non-recourse residential mortgage laws in some key housing markets and contributed to a housing price bubble in those states were an important factor in the housing bubble that kicked off the financial crisis that occurred in the U.S. from the years 2007-2009.

  • Louisiana has a kind of interest in land known as an usufruct, arising from its French civil law tradition, that is absent in other U.S. states. Much of its land also has boundaries with measurements that are round numbers in pre-metric French traditional units of land measurement, rather than the acres, feet, rods, and miles used elsewhere in the U.S.

  • In the parts of the U.S. that were formerly part of Mexico, many states recognize legal rights in land, such as customary hunting and access rights, that arose under Mexican law even though they would not have arisen or existed in legal systems based upon the English common law.

  • In some states, exemplified by Colorado, mineral rights owners who want to mine coal must preserve the surface rights with underground mining tunnels. In other states, exemplified by Wyoming, mineral rights owners who want to mine coal may strip mine the land, destroying the surface rights, so long as the surface is restored somewhat afterwards when the coal seam is exhausted.

  • In parts of the U.S. (largely as a function of different iterations of the Homestead Acts) that were settled sooner, mineral rights are mostly privately owned. In the Mountain states and Alaska, in contrast, the United States government usually reserved mineral rights on homesteaded property and so oil and gas companies and mining companies lease mineral rights from the federal government, rather than from private land owners.

  • Some states organize oil and gas exploitation by units and others do not. State laws on when oil and gas drilling can go diagonally underground from land where the mineral rights user has leased mineral rights varies. The way "use it or lose it" mineral rights lease terms are interpreted varies in subtle but important ways between states.

  • In the arid Western United States, water rights are property rights which have priority based upon the earliest date that a certain amount of water was used by the water rights owner for beneficial use. So, if someone started used X gallons of water per year in 1913 from the Colorado River, they have water rights in that amount with a priority of that date. Elsewhere in the United States, water rights are not generally something that can be bought and sold, and water right priorities depend upon how far up the river basin you are, rather than any pattern of historical use of water.

  • There are many statutory and common law variations on the rule against perpetuities, although the variations show no strong regional pattern.

  • In some major Northeastern cities, especially New York City, multi-family residential housing with multiple owners controlling separate units is often done via what is called a "co-op", while condominium ownership is the norm for these arrangement elsewhere. This is because large Northeastern cities developed an economic demand for owned, multifamily housing before the condominium form of ownership was invented and popularized, and cobbled together the co-op system to meet that need.

  • Major Northeastern cities, especially New York City, also make much greater use of rent control for apartments than elsewhere in the U.S. And, New York City's landlord-tenant laws are so much more protective of tenants' rights than any other jurisdiction that they are almost not recognizable from the perspective of non-NYC landlord-tenant law.

  • Some Great Plains states prohibit corporations from owning farms and ranches.

  • There are significant differences in adverse possession laws from state to state, in the duration of adverse possession required, in the requirement that the adverse possessor must or need not have a good faith belief that the possessor had a claim to own the land, and in the requirement if any to pay compensation to the prior legal owner for adversely possessed land. Some states, but not all, have shortened adverse possession periods under special circumstances such as payment of property taxes while having color of title.

  • There are modest differences between states in the remedies available under particular circumstances if a building or structure encroaches on a neighbor's property or intrudes upon a setback required by a local land use regulation.

  • The law governing trees that encroach on or straddle property lines is absurdly complex, varies greatly from state to state, and is furthermore heavily influenced by local ordinances in addition to state law. Maine has particularly strong prohibitions against harming someone's trees or stone walls.

  • The scope of a seller of property's duty to disclose hazards and latent defects of the property sold to a buyer varies in important fine details from state to state.

Tort Law

Variation in tort laws between states is more modest overall than in the case of property law but is greater than in the case of contract law. There are still many subtle differences between states in their tort laws, but the practical effect and magnitude of these differences tends to be smaller than in the case of property law.

  • A minority of states have no fault insurance systems for minor automobile accidents, while most states do not have no fault insurance for automobile accidents.

  • The question of who can be vicariously liable for an automobile accident when that person wasn't a driver of the car varies considerably between U.S. states. In some states this is only applies to employers of drivers who get into accident on the job and in cases of negligent entrustment. Some states make car owners liable vicariously. Some states have head of household liability for car accidents with a car that belongs to someone in the household. Some states make parents responsible for accidents caused by their minor children.

  • Most U.S. states have one of several minor variations on a comparative fault regime for negligence and product liability lawsuits, which means that the victim and each negligent party has a percentage of fault assigned to them by a judge or jury deciding the case. One major variation within that is whether the negligent parties are jointly and severally liable if other negligent parties are insolvent, or if negligent parties are only liable for their percentage of fault. Another variation is that some states deny relief to victims who are 50% and/or more than 50% at fault, while others do not. In contrast, a minority of U.S. states have the traditional tort liability regime in which someone is either at fault, or not at fault, with contributory negligence by the victim sometimes providing a total defense to a claim for personal injuries.

  • States differ considerably in how failure wear a seat belt limits the recovery available to a victim in a car accident.

  • There are many important but subtle differences in the circumstances under which an attorney can be held liable for professional malpractice, such as the category of persons who have standing to sue for professional malpractice, the extent to which the victim of attorney malpractice has a duty to mitigate damages by various means (e.g. an appeal or settlement), and the time at which a malpractice claim accrues for statute of limitations purposes.

  • States differ in the extent to which hospitals can be held liable for the professional malpractice of medical professions doing medical work at their facilities, and in the extent to which a lead physician in a procedure can be held liable for the negligent acts or failures to act of other people in the team of medical professionals handling a procedure.

  • States differ in how liability is allocated to tortfeasors in toxic tort cases (e.g. toxic chemicals leaking through groundwater from a storage site of the defendant) when there are multiple potentially responsible parties, and in when a statute of limitations accrues in those circumstances.

  • States differ in who they hold responsible for clearing ice and snow in slip and fall personal injury cases, and in particular fact patterns when utilities fail and cause injuries and/or property damage between a clearly utility system main line and a property owner served by those utilities.

  • While almost all states have a worker's compensation regime that imposes strict liability on employers for work related injuries and illnesses in exchange for a fairly stingy measure of damages if the employer obtains worker's compensation insurance, the remedies available to employees whose employer do not obtain worker's compensation insurance, the kinds of employees who are exempt from being covered by worker's compensation insurance, and the circumstances under which a property owner can be held liable for workplace injuries of worker's whose employer (who is a contractor or subcontractor for a property owner) doesn't have worker's compensation insurance, varies considerably from state to state.

  • Some states have restrictive caps on non-economic damages (e.g. pain and suffering, and emotional distress) and/or punitive damages, in tort cases, while others do not have these limitations, or have more lenient limitations.

  • Tort law rights of publicity claims vary greatly from state to state. California is particularly protective of publicity rights.

  • States differ considerably regarding which privacy torts have been adopted in the state.

  • A handful of states still allow lawsuits to be brought on one or more of the historical "heart balm torts" (like alienation of affections), and about half of them that retain those torts greatly restrict the conditions under which damages can be awarded and the amount of damages that can be awarded. At the other extreme, in Colorado and perhaps a few other states, it is a crime to file a heart balm tort action or to seek to secure a settlement for a heart balm tort claim.

  • Some states have premises liability regimes broken up into the traditional classification of plaintiffs as invitees, licensees, and trespassers with different duties owed to each class of plaintiff, while other states use a single negligence standard for all premises liability cases. Many states also statutorily limit liability to wrong doers and criminals on the premises.

  • Conversion and trespass torts, respectively, are strict liability torts in some states and are require a showing of intentional conduct in others.

  • Some states allow trespass and battery claims to prevail without proof of damages, awarding nominal damages in those cases, while other states require proof of damages on those claims to establish liability for those claims.

  • Some states (mostly in the West) exempt people who are traveling by boat on a river or lake from trespassing liability or crimes if they don't set foot on the ground below the water, while in other states, going onto water in a boat over someone else's property is still trespassing.

  • In cases where animals owned by someone cause personal injuries or property damage, some states (mostly in the West) are "fence out" states, where these is a duty to have a fence to keep animals off your property, while other states (mostly in the East) are "fence in" states where animal owners have a duty to keep their animals on their own property.

  • Some states measure damages for tortious harm to pets by the fair market value of the pet, while others allow for some measure of the sentimental value or emotional distress to be added to the purely economic market value of a pet that is killed or injured by tortious conduct.

  • The availability and scope of the negligent infliction of emotional distress tort varies greatly from state to state.

  • Only one or two states have a general tort duty to rescue an unrelated stranger, although a minority of additional states also have duties to rescue strangers or to call for help in certain narrowly defined circumstances.

  • Many states have special limitations (sometimes substantive, sometimes procedural, and sometimes both) on tort liability for volunteers, for good samaritans, for medical professionals, for licensed professionals, and/or for construction work, that differ materially in details from state to state. There are also special limits on liability that vary considerably related to participation in dangerous activities.

  • There are subtle but important differences between states related to the circumstances under which a claim for bad faith breach of contract by a liability insurance company can be established and the proper measure of damages in these cases.

  • Liability for mishandling dead bodies varies considerably from state to state.

  • Procedural and substantive regulation of state and local government liability for tortious conduct other than violations of federal law rights varies considerably from state to state, particularly in the area of liability for wrongful criminal prosecutions and wrongful convictions.

  • Some states statutorily bar fraud or negligent misrepresentation liability for failing to disclose that real estate is reputed to be haunted or had prior incidents associated superstitiously with ghosts (such as prior murders on the premises), while others do not categorically bar liability based upon these torts in these circumstances.

  • The circumstances under which a tort accrues for statute of limitations purposes varies somewhat in subtle ways, particularly related to what constitutes discovery of a tort, and whether a tort is considered to be a one time incident when it first occurs, or is treated as a continuing violation.

  • States vary considerably in the circumstances under which claims for the sexual abuse of children can be brought by the victims against the perpetrators, and there is even more variation in the circumstances under which these claims can be brought against potentially culpable or responsible third-parties. Some states have vicarious liability for third-parties, some states require a showing of negligence by the third-party, and some states bar or greatly limit third-party liability for this conduct.

  • States differ in some particulars of what constitutes a tortious nuisance.

  • States differ in the extent to which parents have liability for the tortious conduct of their minor and/or incompetent children.

  • States differ in the circumstances under which self-defense, defense of others, or defense of property can establish an affirmative defense to tort liability. Some states are "stand your ground" states, some states allow the use of deadly force to protect both a house or a business, while others limit it to just a home and also impose a duty to retreat where feasible.

Contract Law

On the whole, there is less interstate variation in contract law than there is in property law or in tort law.

  • Non-competition agreements are the most enforceable in the Northeast, and are the least enforceable in the West, especially in the Pacific states. Other states tend to fall in between these extremes.

  • Montana, unlike all other U.S. states, prohibits "at will" employment contracts.

  • California has particularly protective consumer protection laws and is the most hostile to arbitration clauses within the very limited discretion afforded to it by the Federal Arbitration Act.

  • Colorado has an outlier aggressively strong statute of frauds that prohibit promises by financial institutions to lend money from being enforced if they are not in writing, notwithstanding even recorded oral representations that it would otherwise constitute fraud to deny.

  • Usury and consumer finance laws vary significantly from one state to another. North Dakota's laws on these subjects are particularly lenient in allowing high interest rates. The legality of payday loans and car title loans differs greatly from state to state.

  • Some states permit contracts to contain confession of judgment remedies, while other states hold that these provisions are void because they are contrary to public policy.

  • The circumstances when a third-party beneficiary of a contract can enforce it varies considerably (with no really strong regional pattern) in cases of warranties arising from a sale of goods under the Uniform Commercial Code, and in the case of contractual relationships with attorneys.

  • Some states do not require proof of damages to prevail in a breach of contract case, awarding nominal damages of $1 if a breach of contract is proven but no damages can be shown, while other states make proof of damages an element of a claim for breach of contract.

  • In some states, contract terms requiring modifications to a contract to be in writing, even if the contract isn't otherwise subject to the statute of frauds, are valid, while in other states, such contract terms are void as contrary to public policy.

  • Some states allow recoveries on an unjust enrichment or promissory estoppel theory if contract formation can't be established or their is a prior breach of contract by the party seeking relief, more easily than other states.

  • There are modest differences between states in the kinds of contracts or contract modifications that don't require a showing that they are supported by consideration.

  • There are modest differences in the circumstances under which a contract may be established by a course of dealings without specific proof of an offer and acceptance.

  • There are considerable differences between states regarding the circumstances under which assisted reproduction and sperm donor contracts are valid and enforceable.

  • There are considerable differences between states regarding the circumstances under which a "palimony" claim can be established.

  • States differ in the formalities necessary to enter into a valid prenuptial agreement.

  • There are differences between states regarding the circumstances under which choice of law and choice of forum clauses in contracts can be disregarded as contrary to public policy.

  • Some states have laws allowing certain kinds of consumer contracts to be unilaterally rescinded by a consumer within a certain number of days (in addition to the federal laws granting these rights in some circumstances), or requiring certain notices before making automatic credit card or bank charges.

  • State differ in the circumstances under which a contract between a client and an attorney, or certain terms in those contracts, can be rendered void for lack of informed consent.

  • States differ in the circumstances under which a contract to perform services entered into by someone who lacks a legally required license to perform those services can enforce that contract.

  • States differ regarding what kind of contract drafting activities constitute the unauthorized practice of law when done by a non-lawyer. Generally speaking, Eastern states are more strict and Western states are more lenient.

  • States differ in the formalities required to transfer horses and livestock of types that are often branded. States with large ranching and horse breeding industries tend to regulate these transfers more heavily.

  • 2
    Here's another for the property section: In Maine, Massachusetts, and Delaware, coastal private property interests extend to the low tide mark, while in all other coastal states, they extend only to the high tide mark. Commented Jan 30 at 20:44
  • @A.R. A good example.
    – ohwilleke
    Commented Jan 30 at 21:44

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