Quantum meruit is a Latin phrase meaning "what one has earned". In the context of contract law, it means something along the lines of "reasonable value of services".

In the United States, the elements of quantum meruit are determined by state common law. For example, to state a claim for unjust enrichment in New York, a plaintiff must allege that (1) the defendant was enriched; (2) the enrichment was at plaintiff's expense; and (3) the circumstances were such that equity and good conscience require defendants to make restitution.

In laws of equity, unjust enrichment occurs when one person is enriched at the expense of another in circumstances that the law sees as unjust. Where an individual is unjustly enriched, the law imposes an obligation upon the recipient to make restitution, subject to defences such as change of position. Liability for an unjust (or unjustified) enrichment arises irrespective of wrongdoing on the part of the recipient. The concept of unjust enrichment can be traced to Roman law and the maxim that "no one should be benefited at another's expense": nemo locupletari potest aliena iactura or nemo locupletari debet cum aliena iactura.

The law of unjust enrichment is closely related to, but not coextensive with, the law of restitution. The law of restitution is the law of gain-based recovery. It is wider than the law of unjust enrichment. Restitution for unjust enrichment is a subset of the law of restitution in the same way that compensation for breach of contract is a subset of the law relating to compensation.

A covenant, in its most general sense and historical sense, is a solemn promise to engage in or refrain from a specified action. Under historical English common law a covenant was distinguished from an ordinary contract by the presence of a seal. Because the presence of a seal indicated an unusual solemnity in the promises made in a covenant, the common law would enforce a covenant even in the absence of consideration. In United States contract law, an implied covenant of good faith is presumed.

A covenant is a type of agreement analogous to a contractual condition. The covenantor makes a promise to a covenantee to perform (affirmative covenant (American) / positive covenant (England and Wales)) or to refrain from (negative covenant) some action. In real property law, the juristic term real covenants means conditions tied to the ownership or use of land. A "covenant running with the land", meeting tests of wording and circumstances laid down in precedent, imposes duties or restrictions upon the use of that land regardless of the owner. Restrictive covenants are somewhat similar to easements and equitable servitudes, leading to some discussion about whether these concepts should be unified; in the US the Restatement (Third) of Property takes steps to merge these concepts as servitudes. Real covenant law in the US has been referred to as an "unspeakable quagmire" by one court.

Covenants for title are covenants which come with a deed or title to the property, in which the grantor of the title makes certain guarantees to the grantee. Non-compete clauses in the United States are also called restrictive covenants.

Landlords may seek and courts may grant forfeiture of leases such as in leasehold estates for breach of covenant, which in most jurisdictions must be relatively severe breaches; however, the covenant to pay rent is one of the more fundamental covenants. The forfeiture of a private home involves interference with social and economic human rights. In the case of leases commuted to a large sum payable at the outset (a premium), this has prompted lobbying for and government measures of leasehold reform particularly in the law of ground rents and service charges.

Local government in the United States refers to governmental jurisdictions below the level of the state. Most states and territories have at least two tiers of local government: counties and municipalities. In some states, counties are divided into townships. There are several different types of jurisdictions at the municipal level, including the city, town, borough, and village. The types and nature of these municipal entities vary from state to state. In addition to these general-purpose local governments, states may also create special-purpose local governments.

Many rural areas and even some suburban areas of many states have no municipal government below the county level. In other places consolidated city-county jurisdictions exist, in which city and county functions are managed by a single municipal government. In places like New England, towns are the primary unit of local government and counties have no governmental function but exist in a purely perfunctory capacity (for example, for census data).

In addition to counties and municipalities, states often create special purpose authorities, such as school districts and districts for fire protection, sanitary sewer service, public transportation, public libraries, public parks or forests, or water resource management. Such special purpose districts may encompass areas in multiple municipalities or counties. According to the US Census Bureau's data collected in 2012, there were 89,004 local government units in the United States. This data shows a decline from 89,476 units since the last census of local governments performed in 2007.

Depending on the state, local governments may operate under their own charters or under general law, or a state may have a mix of chartered and general-law local governments. Generally, in a state having both chartered and general-law local governments, the chartered local governments have more local autonomy and home rule.

A lie is a statement used intentionally for the purpose of deception. The practice of communicating a lie is called lying; a person who communicates a lie may be termed a liar. Lies may be employed to serve a variety of instrumental, interpersonal, or psychological functions for the individuals who use them. Generally, the term "lie" carries a negative connotation and, depending on the context, a person who communicates a lie may be subject to social, legal, religious, or criminal sanctions. 

Authentication, in the law of evidence, is the process by which documentary evidence and other physical evidence is proven to be genuine, and not a forgery. Generally, authentication can be shown in one of two ways. First, a witness can testify as to the chain of custody through which the evidence passed from the time of the discovery up until the trial. Second, the evidence can be authenticated by the opinion of an expert witness examining the evidence to determine if it has all of the properties that it would be expected to have if it were authentic.

Chain of custody (CoC), in legal contexts, is the chronological documentation or paper trail that records the sequence of custody, control, transfer, analysis, and disposition of materials, including physical or electronic evidence. Of particular importance in criminal cases, the concept is also applied in civil litigation and more broadly in drug testing of athletes and in supply chain management, e.g. to improve the traceability of food products, or to provide assurances that wood products originate from sustainably managed forests. It is often a tedious process that has been required for evidence to be shown legally in court. Now however, with new portable technology that allows accurate laboratory quality results from the scene of the crime, the chain of custody is often much shorter which means evidence can be processed for court much faster.

The term is also sometimes used in the fields of history, art history, and archives as a synonym for provenance (meaning the chronology of the ownership, custody or location of a historical object, document or group of documents), which may be an important factor in determining authenticity.

Judicial notice is a rule in the law of evidence that allows a fact to be introduced into evidence if the truth of that fact is so notorious or well known, or so authoritatively attested, that it cannot reasonably be doubted. This is done upon the request of the party seeking to rely on the fact at issue. Facts and materials admitted under judicial notice are accepted without being formally introduced by a witness or other rule of evidence, and they are even admitted if one party wishes to plead evidence to the contrary.

The best evidence rule is a legal principle that holds an original of a document as superior evidence. The rule specifies that secondary evidence, such as a copy or facsimile, will be not admissible if an original document exists and can be obtained. The rule has its roots in 18th-century British law.

A self-authenticating document, under the law of evidence in the United States, is any document that can be admitted into evidence at a trial without proof being submitted to support the claim that the document is what it appears to be. Several categories of documents are deemed to be self-authenticating:

1. Certified copy of public or business records;

2. Official publications of government agencies;

3. Newspaper articles;

4. Trade inscriptions, such as labels on products;

5. Acknowledged documents (wherein the signer also gets a paper notarized); and

6. Commercial paper under the Uniform Commercial Code.

Robbery is the crime of taking or attempting to take anything of value by force, threat of force, or by putting the victim in fear. According to common law, robbery is defined as taking the property of another, with the intent to permanently deprive the person of that property, by means of force or fear; that is, it is a larceny or theft accomplished by an assault. Precise definitions of the offence may vary between jurisdictions. Robbery is differentiated from other forms of theft (such as burglary, shoplifting, pickpocketing, or car theft) by its inherently violent nature (a violent crime); whereas many lesser forms of theft are punished as misdemeanors, robbery is always a felony in jurisdictions that distinguish between the two. Under English law, most forms of theft are triable either way, whereas robbery is triable only on indictment. The word "rob" came via French from Late Latin words (for example, deraubare) of Germanic origin, from Common Germanic raub "theft".

Among the types of robbery are armed robbery, which involves the use of a weapon, and aggravated robbery, when someone brings with them a deadly weapon or something that appears to be a deadly weapon. Highway robbery or mugging takes place outside or in a public place such as a sidewalk, street, or parking lot. Carjacking is the act of stealing a car from a victim by force. Extortion is the threat to do something illegal, or the offer to not do something illegal, in the event that goods are not given, primarily using words instead of actions.

Criminal slang for robbery includes "blagging" (armed robbery, usually of a bank) or "stick-up" (derived from the verbal command to robbery targets to raise their hands in the air), and "steaming" (organized robbery on underground train systems).

Promissory estoppel.

The doctrine of promissory estoppel prevents one party from withdrawing a promise made to a second party if the latter has reasonably relied on that promise.

A promise made without consideration is generally not enforceable. It is known as a bare or gratuitous promise. Thus, if a car salesman promises a potential buyer not to sell a certain car over the weekend, but does so, the promise cannot be enforced. But should the car salesman accept from the potential buyer even one penny in consideration for the promise, the promise will be enforceable in court by the potential buyer. Estoppel extends the court's purview even to cases where there is no consideration, though it is generally not a 'sword': not a basis on which to initiate a lawsuit.

In English jurisprudence, the doctrine of promissory estoppel was first developed in Hughes v Metropolitan Railway Co  but was lost for some time until it was resurrected by Denning J in the controversial case of Central London Property Trust Ltd v High Trees House Ltd.

Promissory estoppel requires:

1. an unequivocal promise by words or conduct;

2. evidence that there is a change in position of the promisee as a result of the promise (reliance but not necessarily to their detriment); and

3. inequity if the promisor were to go back on the promise.

In general, estoppel is "a shield not a sword"—it cannot be used as the basis of an action on its own. It also does not extinguish rights. In High Trees the plaintiff company was able to restore payment of full rent from early 1945 and could have restored the full rent at any time after the initial promise was made provided a suitable period of notice had been given. In this case, the estoppel was applied to a "negative promise", that is, one where a party promises not to enforce full rights.

Estoppel is an equitable (as opposed to common law) construct and its application is therefore discretionary. In the case of D & C Builders v Rees the courts refused to recognize a promise to accept a part payment of £300 on a debt of £482 on the basis that it was extracted by duress. In Combe v Combe Denning elaborated on the equitable nature of estoppel by refusing to allow its use as a "sword" by an ex-wife to extract funds from the destitute husband.

The general rule is that when one party agrees to accept a lesser sum in full payment of a debt, the debtor has given no consideration, and so the creditor is still entitled to claim the debt in its entirety. This is not the case if the debtor offers payment at an earlier date than was previously agreed, because the benefit to the creditor of receiving payment early can be thought of as consideration for the promise to waive the rest of the debt. This is the rule formulated in Pinnel's Case, and affirmed in Foakes v Beer.

The decision of the Court of Appeal in Collier v P & MJ Wright (Holdings) Ltd suggests that the doctrine of promissory estoppel can now operate to mitigate the harshness of this common law rule. Moreover, Arden LJ held that allowing a creditor to renege on his promise to forebear seeking the balance of a debt in return for part payment would be, in and of itself, inequitable. Therefore, the only reliance that the promisee must demonstrate is the actual making of the part payment. This approach has been criticised as doing violence to the principle set down in Hughes and the extent to which the other members of the Court, namely Longmore LJ, agreed with it is uncertain.

An easement is a nonpossessory right to use and/or enter onto the real property of another without possessing it. It is "best typified in the right of way which one landowner, A, may enjoy over the land of another, B". It is similar to real covenants and equitable servitudes; in the United States, the Restatement (Third) of Property takes steps to merge these concepts as servitudes.

Easements are helpful for providing pathways across two or more pieces of property, allowing individuals to access other properties or a resource, for example to fish in a privately owned pond or to have access to a public beach. An easement is considered as a property right in itself at common law and is still treated as a type of property in most jurisdictions.

The rights of an easement holder vary substantially among jurisdictions. Historically, the common law courts would enforce only four types of easement:

Right-of-way (easements of way),

Easements of support (pertaining to excavations),

Easements of "light and air", and,

Rights pertaining to artificial waterways.

Modern courts recognize more varieties of easements, but these original categories still form the foundation of easement law.

When the Court grants a cert petition, the case is set for oral argument. Both parties will file briefs on the merits of the case, as distinct from the reasons they may have argued for granting or denying the cert petition. With the consent of the parties or approval of the Court, amici curiae, or "friends of the court", may also file briefs. The Court holds two-week oral argument sessions each month from October through April. Each side has thirty minutes to present its argument (the Court may choose to give more time, though this is rare), and during that time, the Justices may interrupt the advocate and ask questions. The petitioner gives the first presentation, and may reserve some time to rebut the respondent's arguments after the respondent has concluded. Amici curiae may also present oral argument on behalf of one party if that party agrees. The Court advises counsel to assume that the Justices are familiar with and have read the briefs filed in a case.

Supreme Court bar.

In order to plead before the court, an attorney must first be admitted to the court's bar. Approximately 4,000 lawyers join the bar each year. The bar contains an estimated 230,000 members. In reality, pleading is limited to several hundred attorneys. The rest join for a one-time fee of $200, earning the court about $750,000 annually. Attorneys can be admitted as either individuals or as groups. The group admission is held before the current justices of the Supreme Court, wherein the chief justice approves a motion to admit the new attorneys. Lawyers commonly apply for the cosmetic value of a certificate to display in their office or on their resume. They also receive access to better seating if they wish to attend an oral argument. Members of the Supreme Court Bar are also granted access to the collections of the Supreme Court Library.

Decision.

At the conclusion of oral argument, the case is submitted for decision. Cases are decided by majority vote of the Justices. It is the Court's practice to issue decisions in all cases argued in a particular term by the end of that term. Within that term, however, the Court is under no obligation to release a decision within any set time after oral argument.

After the oral argument is concluded, usually in the same week as the case was submitted, the Justices retire to another conference at which the preliminary votes are tallied and the Court sees which side has prevailed. One of the Justices in the majority is then assigned to write the Court's opinion—also known as the "majority opinion". This assignment is made by the most senior Justice in the majority (with the Chief Justice always being considered the most senior). Drafts of the Court's opinion circulate among the Justices until the Court is prepared to announce the judgment in a particular case. Justices are free to change their votes on a case up until the decision is finalized and published. In any given case, a Justice is free to choose whether or not to author an opinion or else simply join the majority or another Justice's opinion. There are several primary types of opinions:

Opinion of the Court: this is the binding decision of the Supreme Court. An opinion that more than half of the Justices join (usually at least five Justices, since there are nine Justices in total; but in cases where some Justices do not participate it could be fewer) is known as "majority opinion" and creates binding precedent in American law. Whereas an opinion that fewer than half of the Justices join is known as a "plurality opinion" and is only partially binding precedent.

Concurring: when a Justice "concurs", he or she agrees with and joins the majority opinion but authors a separate concurrence to give additional explanations, rationales, or commentary. Concurrences do not create binding precedent.

DNA profiling (also called DNA fingerprinting) is the process of determining an individual's DNA characteristics. DNA analysis intended to identify a species, rather than an individual, is called DNA barcoding.

DNA profiling is a forensic technique in criminal investigations, comparing criminal suspects' profiles to DNA evidence so as to assess the likelihood of their involvement in the crime. It is also used in parentage testing, to establish immigration eligibility, and in genealogical and medical research. DNA profiling has also been used in the study of animal and plant populations in the fields of zoology, botany, and agriculture.

Possession of stolen goods is a crime in which an individual has bought, been given, or acquired stolen goods.

In many jurisdictions, if an individual has accepted possession of goods or property and knew they were stolen, then the individual is typically charged with a misdemeanor or felony, depending on the value of the stolen goods and the good and or property is returned. If the individual did not know the goods were stolen, then the goods are returned to the owner and the individual is not prosecuted. However, there are often exceptions, because of the difficulty of proving or disproving an individual's knowledge that the goods were stolen.