# US Copyright Law

Copyrights are rights to copy, distribute, display and perform creative works. They are one of the basic forms of intellectual property.
This text discusses copyright law as it applies in the United States. This concise presentation necessarily omits a number of important provisions of a very complex area of law.

## Introduction

American copyright law traces its lineage to the English Statute of Anne, passed in 1710. The Statute provided that authors of books had an exclusive right to their works for fourteen years, which could be renewed by the author for an additional fourteen years.
After the American Revolution, many states passed statutes modeled on the Statute of Anne. Because the laws were different from state to state, the Constitutional Convention decided that the new Congress should have the power to pass a national copyright statute, and added a clause in Article I to that effect. The statute was enacted as the Copyright Act of 1790, one of Congress's first laws. Like the Statute of Anne, it provided a 14-year initial term, renewable for an additional 14 years, and it only applied to books, maps, and (maritime) charts. Over the next century, the 1790 Act was expanded to cover other types of works.
There was a full revision of the copyright laws in 1870, and after that the next major revision of the Act was passed as the Copyright Act of 1909. The 1909 Act doubled the term of copyrights to 28 years, renewable for an additional 28, and expanded protection to cover all written works in the US as well as many foreign works. Both the 1790 Act and the 1909 Act required a number of formalities before copyright would attach: these formalities are described later.
The Copyright Act of 1976 formed the basic copyright law regime which the US follows today. It provided a single copyright term for works created after 1977: the life of the author, plus fifty years (seventy-five years from fixation in the case of works made for hire). It eliminated many of the required formalities and applied copyright at the moment the work was "fixed" in a tangible medium of expression.
Since then, the main revisions to the 1976 Act have been the Audio Home Recording Act of 1992, adding new laws pertaining to digital audio recordings; the Sonny Bono Copyright Term Extension Act of 1998, extending the term of copyright for an additional twenty years (see Duration); and the Digital Millennium Copyright Act of 1998, imposing new rules on high-tech works.

## Copyrightable Works

To be copyrightable, a work must be an original work of authorship that is fixed in a tangible medium of expression. These requirements are often shortened to creativity and fixation.

### Original works of authorship

An original work of authorship can be just about anything. 17 U.S.C. § 102(a) lists eight basic kinds, by way of example:
* Literary works - Any work expressed in letters, numbers, or symbols, regardless of medium. This Wikibook is a literary work under the Copyright Act. Computer source code is also considered to be a literary work. If a literary work is fictional, its characters, plot, structure and other devices can be copyrighted along with the actual text, but only to the extent that they are original and expressive.
* Musical works - Original musical compositions. Actual performances of music are covered as a different type of work, a "sound recording." 17 U.S.C. § 115 provides that anyone may create a sound recording of any composition, so long as they pay that composer a set licensing fee.
* Dramatic works - Distinguished from literary works in that they direct a performance through written instructions.
* Choreographic works - Added in the 1976 Act. They must be "fixed," either through notation or video recording.
* Pictorial, graphic and sculptural works - Any two-dimensional or three-dimensional art work may be copyrighted as a PGS work. These works are constrained by the "useful article doctrine" described below, which serves to keep copyright and patent law divided.
* Audiovisual works - Includes films, television programs and any other work that combines audio and visual components.
* Sound recordings - Any magnetically or digitally recorded audio work (except the accompanying audio to a visual work, which is treated as part of the audiovisual work). Unlike musical works, there is no statutory licensing of sound recordings. While anyone may produce a rendition of an artist's composition by paying him the statutory fee, they may not reproduce his recordings without his express permission.
* Architectural works - Added in the 1976 Act. Copyright in architectural works only extends to aesthetics. If a design element is "functionally required," it is not protected by copyright. See H.R. Rep. No. 101-735 (1990) and "Useful article doctrine," below.

#### Idea vs. expression

Copyright protects creative and useful expression in an author's article, but it does not protect the ideas expressed in that article. By consuming a work, a reader may learn a number of "facts," things asserted as true by the work. The "facts" related within are in the public domain and free for anyone else to disseminate. Consider a hypothetical biography of William Henry Harrison. This book may certainly contain the fact, learned from another work, that Harrison was considered more of a showman than a serious political candidate in his day, but this book may not use the specific wording used in the original biography without permission of the person holding its copyright.
Of course, that is a historical record, and maybe it seems natural that someone cannot copyright the details of that man's life. In the fictional realm, it may seem natural that the author can control the facts of their novel because the plot is their creative work. This is not the case, although a more nuanced analysis is required for fictional facts. This does not even have anything to do with Fair Use: the individual ideas in the story are simply not covered by copyright while the whole of them is. As long as the later work does not have exactly the same plot, similarities are allowed, and the later work may also discuss the facts of the earlier work with impunity.

#### Facts vs. Compilations

Copyright does not protect recording of facts that are "common property" and contain no "original authorship". Some examples are standard calendars, tape measures and rulers, height and weight charts, and lists or tables taken from public documents or other common sources. For example a recipe which contains only a list of ingredients is not copyrightable, but a recipe contains elements of original authorship such as explanations, instructions, and illustrations can be copyrighted.
On the other hand compilations of facts such as dictionaries and even telephone directories can receive copyright protection. But the facts themselves cannot be copyrighted—only the expression of those facts can be copyrighted. This means that many database providers may not be able to rely on copyright to protect their data from being republished: they must rely on licenses and other elements of contract law. In other cases, the law of unfair competition can prevent one business from using another's compilations of information in an unfair way. See Intl. News Serv. v. Associated Press, 248 U.S. 215 (1918) (holding that INS could not re-report AP news stories on the West Coast for commercial advantage).
In the realm of software, source code and object code are copyrightable, but other elements of a program may not be. User interfaces, for instance, are generally not copyrightable: see Apple Computer v. Microsoft, 35 F.3d 1435 (9th Cir. 1994) (icons and desktop appearance of Windows not copyrightable); Lotus Development v. Borland Intl., 49 F.3d 807 (1st Cir. 1995) (menu structure of Lotus 1-2-3 not copyrightable).

#### Useful article doctrine

Many pictorial, graphic and sculptural works are also patentable as useful inventions. If the creative component of a work cannot be separated from its functional component, it is considered an industrial design and it cannot be copyrighted. This is known as conceptual separability. One well-known example is the Brandir Ribbon bicycle rack, which adopted an artistic design quite different from previous bicycle racks. Because the creativity of the design was inseparable from its functionality, the rack was deemed protectable only through patent law. Brandir Intl. v. Cascade Pacific Lumber, 834 F.2d 1142 (2d Cir. 1987). For more on patents, see the Wikibook on US Patent Law.

#### Government works

Works of the U.S. federal government are not copyrighted. 17 U.S.C. § 105; see also Wheaton v. Peters, 33 U.S. 591 (1834) (official reporter of the Supreme Court unable to protect annotations of Supreme Court opinions).
State statutes and court opinions are generally considered to be public domain as well, because of a public policy interest in allowing citizens unrestricted access to the law. See Nash v. Lathrop, 6 N.E. 559 (Mass. 1886) (state statutes held to be public domain); Veeck v. Southern Bldg. Code Cong. Intl., 293 F.3d 791 (5th Cir. 2002) (model statutes enter public domain when enacted).
However, other state government works can be copyrighted when the creator of the work needs an economic incentive; see Co. of Suffolk v. First Am. Real Estate Solutions, 261 F.3d 179 (2d Cir. 2001) (county allowed to hold copyright in tax maps).

### Fixation

Fixation requires that the work be recorded in a form that can be perceived directly or by means of a device "now known or later developed." Writing, drawing, sculpting, recording and making notations all count as fixation. Improvisational and/or unrecorded performances of music, dance or drama are likely to be creative but not fixed. Something that is typed on a computer but never saved to a permanent storage medium might also be unfixed (but once the work is saved, it is fixed). Oddly, ice sculptures are not adequately fixed to warrant copyright protection, but RAM copies of data are adequately fixed.
The US copyright office, in the Compendium of US Copyright Law, notes the following (rare) examples of works that have not been adequately "fixed" for copyright purposes:
"Choreography that has never been filmed or notated." "An extemporaneous film that has not been filmed or recorded." "A work communicated solely through conversation . . .."

### References

* ↑ http://www.copyright.gov/circs/circ01.pdf
* ↑ http://www.copyright.gov/help/faq/faq-protect.html#recipe

## Formalities

Under the 1790 and 1909 Acts, formalities were a necessary prerequisite to copyright protection. The 1976 Act made many of these formalities unnecessary to receive protection, and since US accession to the Berne Convention, formalities are generally not required for copyright protection, although they give the copyright holder some distinct advantages if followed. There are three sets of rules for formalities:
* Works created before January 1, 1978 follow the rules of the 1909 Act.
* Works created between January 1, 1978 and March 1, 1989 follow the rules of the 1976 Act.
* Works created after March 1, 1989 follow the rules of the Berne Convention Implementation Act.

### Notice

The 1909 Act required that all published works carry the "©" symbol or the word "Copyright," the year of first publication, and the name of the author in order to receive copyright. Several years may be noted in the case of multiple completion dates - e.g., in the case of further editing. The 1976 Act eased the particularities of the notice requirement, but kept it as a prerequisite to copyright protection.
Today, notice is not a requirement. The Berne Convention Implementation Act of 1989 made notice unnecessary on all works first published after March 1, 1989. Notice is still encouraged by the law, however. If a work carries copyright notice, the notice bars other parties from claiming "innocent infringement" as a defense. 17 U.S.C. § 401. Practically, this means that an author who has registered a copyright on the work may sue for punitive damages.

### Publication

Under the 1909 Act, publication had two important legal purposes: it applied federal copyright protection to the work, and it removed common law copyright protection. Courts eventually determined that there were two types of publication. Investive publication, the type that would apply federal protection, did not have to be widespread: it could be among a small group of people. Federal protection would not attach unless notice and other formalities were followed, but in the absence of such formalities, common law protection would still apply. Divestive publication, the type that would remove common law protection, had to be on a larger, more general scale.
The 1976 Act changed the law so that federal copyright protection attaches upon fixation, not publication. This eliminated the entire concept of investive publication. Divestive publication remained in a different form: if a work was offered to the public without copyright notice and other formalities, it would lose its copyright protection under federal law.
Since 1989, publication has had no effect upon the validity of copyright. It still has relevance to post-1989 works: it determines when deposit is required, and it determines the term length for works by corporate authors, among other purposes.

### Registration

Copyright registration has never been a requirement for protection, but it has always been helpful to authors. The most important aspect of registration, which applies under all three copyright regimes, is that registration is a prerequisite to suing for infringement. Note that registration can occur after the infringement itself, but it must be made before any suit is filed.
Under the 1909 Act, registration was also necessary before renewing a copyright. The vast majority of authors did not renew their work, but this stipulation may have prevented those who did not anticipate their work remaining relevant enough for renewing to make a financial difference. In that sense, not registering would have prevented authors from doubling their copyright term for that work.

### Deposit

When a person registers a copyright, they must supply two copies of the work to the Library of Congress. 17 U.S.C. § 408. The deposit requirement also applies to any work published in the United States for which copyright is claimed within three months of publication. 17 U.S.C. § 407.

## Rights
### Rights conferred by copyright

The actual rights contained within a copyright are:
* Right to copy. This right includes all exact or substantially similar reproduction of the work.
* Right to make derivative works. Derivative works include translations, adaptations to other media (for instance, movies based on books, books based on movies, toys based on movies, movies based on other movies, books based on other books, art works based on photographs, etc.), annotations and editorial revisions. Unauthorized derivative works receive no copyright protection, even for their original elements.
* Right to distribute. The author has the right to control the sale and importation of their work, subject to the "first sale doctrine" described under Infringement.
* Right to publicly perform. Performance applies to dynamic works such as drama, music and choreography. Any act that makes such works perceivable to viewers or listeners is a performance; "public" generally means in an environment "open to the public." Note that authors have no performance right in a sound recording, although there is a performance right in musical compositions.
* Right to publicly display. Display applies to static works such as photography and sculpture. Generally, the owner of a copy has the right to display their copy to anyone present at the place where it is located: this means that authors cannot keep art works out of galleries. The display right is generally invoked to stop broader displays of a work, such as on a television broadcast or web site. Note that authors have no display right in architectural works.
* Moral rights. Authors of works of visual art gained the right to attribution and integrity when the U.S. acceded to the Berne Convention in 1989. These rights include the right to "prevent any intentional distortion, mutilation, or other modification" to one's work if it would be prejudicial to the author's honor or reputation. 17 U.S.C. 106A.

### Ownership of copyright

When someone creates a pieces of work, they get to copy right it.
When an individual creates a work within the scope of their employment, their work is considered a work for hire and, in the absence of a contrary provision in the contract, the copyright goes to their employer. The doctrine is governed by the common law of agency, so independent contractors are not considered to be working for hire; see Community for Creative Non-Violence v. Reid, 490 U.S. 730 (1989) . Some works of non-employees may considered to be works for hire, but only "if the parties expressly agree in a written instrument signed by them": such works include translations, contributions to collective works, atlases and parts of motion pictures. 17 U.S.C. § 101. Courts generally except university professors from this rule: they usually have copyright in their work regardless of whether it was made in the scope of their employment. See Hays v. Sony Corp of Am., 847 F.2d 412 (7th Cir. 1988).
When a work has more than one author, the authors can have joint ownership. To receive joint copyright, the authors must each contribute an independently copyrightable contribution, and must intend their contributions be merged into a unitary whole. This is often governed by contracts between authors, but can also be inferred from the parties' roles in the creation of the work; see Aalmuhammed v. Lee, 202 F.3d 1227 (9th Cir. 2000).
Collective works such as periodicals, anthologies and encyclopedias can be copyrighted independently of their contributions. The authors retain copyright in their individual contributions, but the compiler has copyright in the entire collective work. 17 U.S.C. § 201(c).

#### Duration

The length of copyright has changed over the 20th century. The most recent legislation, the Sonny Bono Act of 1998, extended copyright terms for an additional 20 years after intense lobbying by the entertainment industry. This was challenged on constitutional grounds (that Congress could not keep extending copyrights indefinitely), but the Supreme Court's decision in ɛldred v. Ashcroft, 537 U.S. 186 (2003) , held the act to be constitutional. The current duration rules are, in general, as follows:
| Date of creation | Date copyright attaches | Duration of copyright |
| Created before 1978 but unpublished | January 1, 1978 | Life of the author plus 70 years |
| Published between 1923 and 1963 | Date of publication | 28 years, with an option to renew for 67 years. If not renewed, public domain. |
| Published between 1964 and 1977 | Date of publication | 95 years |
| Created 1978 or later | Date of fixation | For individual authors, life of the author plus 70 years. For corporate or anonymous authors, 95 years from publication OR 120 years from creation, whichever is less. |

#### Division and transfer

A copyright can be divided and given to others. This was not always the case: under the 1909 Act, a copyright was only transferable in its entirety: transferring part of a copyright was interpreted as a license, akin to a lease of property. Under the 1976 Act, a transfer of a copyright or part of a copyright is valid if executed in writing and signed by the copyright owner. 17 U.S.C. § 204.
The Copyright Act also contains provisions for termination of transfer in 17 U.S.C. §§ 203 and 304(c). These provisions allow the original author of many types of work to "take back" their copyright at a certain date after transferring it.
* Authors of works created after 1977 may terminate transfers between the 35th and 40th year following the execution of the transfer.
* Authors of works created before 1978 may terminate transfers between the 56th and 61st year of copyright protection.
* The transfer to an employer of a work made for hire may not be terminated. This includes all motion pictures, sound recordings and contributions to collective works (e.g. magazines and anthologies).

## Infringement
### Infringement of right to copy

To find infringement of the right to copy, a court must find copying and improper appropriation of the copyrighted work by the accused infringer.

#### Copying

Independent creation of a copyrighted work is not considered to be copying. This means that copying cannot be proven from similarity alone. There are two ways to prove copying.
The first is through direct evidence. Some authors (especially authors of factual compilations such as phone books) plant minor errors in their works so there will be obvious evidence of any copying. In other cases, there may be evidence of the infringer's admission to copying.
The other way to prove copying is through circumstantial evidence. The factors in this analysis are access and similarity. If the author of the accused work had access to the original, and the accused work has sufficient similarities to the original, a court can conclude that copying took place.

#### Improper appropriation

While copying is a fairly straightforward analysis, improper appropriation is often more difficult. When a work is copied word for word (or bit for bit), the copying can generally be considered to be improper appropriation. The more difficult case is when only part of a work is copied—for example, when characters or plot devices from a literary work, or a chord progression or melody from a musical composition, are copied to create a derivative work.
The key to improper appropriation is substantiality of the copying. Copying an insubstantial part of a work is not likely to constitute infringement. Whether copying is substantial is still a difficult question. In Nichols v. Universal Pictures, 45 F.2d 119 (2d Cir. 1930), Judge Learned Hand concluded that "the proper approach" in answering the question must be "more like that of a spectator, who would rely upon the complex of his impressions of each character." This is known as the subjective test for improper appropriation. Some other courts, particularly in the Ninth Circuit, apply an objective test that compares each copyrightable element of the two works to determine to what extent the accused work copies the original.
Note also that in some circumstances, certain works or certain parts of works can legally be copied under the fair use doctrine, discussed later.

### Infringement of right to distribute

Copyright owners also have the sole right to distribute copies of their work, whether through sales or otherwise. This includes the right to import: 17 U.S.C. § 602 bans unauthorized importation of copyrighted works, except for certain personal or educational uses.
The key exception to this right is the first sale doctrine. Once a legal copy is sold, the copyright holder has no further control over the distribution of that particular copy of the work. For example, one who purchases a book may re-sell that book without violating the copyright holder's section 106(3) distribution right. The only exceptions to this doctrine are sound recordings and computer programs, which cannot be rented out even after their first sale. 17 U.S.C. § 109.

### Contributory and vicarious infringement

Contributory infringement is a common law doctrine famously stated in Gershwin Publishing v. Columbia Artists Mgmt., 443 F.2d 1159 (2d Cir. 1971): "One who, with knowledge of the infringing activity, induces, causes or materially contributes to the infringing conduct of another, may be held liable as a 'contributory' infringer." Vicarious infringement is a separate but related doctrine applied to those who have the power to halt infringing conduct, and derive a financial benefit from the infringing conduct.
The two doctrines can be found together, but can also be found separately. Contributory infringement is a tort doctrine; it requires knowledge and participation. Vicarious infringement is more closely related to agency. A person can be liable for vicarious infringement simply because of their relation with the infringer (e.g. an employer can be liable for employees' infringement on the job). Both types of infringement are equivalents of direct infringement.
The most famous contributory and vicarious infringement case is Sony v. Universal City Studios, 464 U.S. 417 (1984) . The Supreme Court was deeply split on the issue, but a 5-4 majority decided that Sony was not liable for contributory infringement from the sale of its Betamax VCRs. "The sale of copying equipment," wrote Justice John Paul Stevens, "like the sale of other articles of commerce, does not constitute contributory infringement if the product is widely used for legitimate, unobjectionable purposes. Indeed, it need merely be capable of substantial noninfringing uses." The Court went on to find that "time shifting," the act of videotaping a broadcast to watch it later, was a form of fair use even if unauthorized, and therefore not infringing. Similar logic was applied to MP3 players in RIAA v. Diamond Multimedia Systems, 180 F.3d 1072 (9th Cir. 1999) (holding "space shifting" to be a substantial noninfringing use).
The rapid growth of the Internet has led to a number of developments in contributory and vicarious infringement law. One early fear was that the doctrines would lead to potentially limitless liability for any person operating a system that processed infringing data. The Digital Millennium Copyright Act of 1998 created a "safe harbor" for ISPs and server operators, protecting them from contributory infringement as long as they (1) have a policy of terminating users who are repeat copyright infringers, (2) adopt standard copyright protection measures, and (3) register an agent with the Copyright Office to receive infringement claims from copyright owners. The safe harbor applies to systems involved in the routing, storing, caching, and linking of copyrighted data.
Despite the safe harbor, some online services have been found liable for contributory and vicarious infringement. The best-known examples are the Napster and Grokster file sharing services, both of which were forced to shut down after they were unable to effectively police their content to stop infringement. A&M Records v. Napster, 239 F.3d 1004 (9th Cir. 2001); MGM Studios v. Grokster, 545 U.S. ___ (2005) .

### Criminal offenses
#### Criminal infringement

17 U.S.C. § 506(a) provides that an infringer faces criminal liability in two situations:
* When their infringement is "for purposes of commercial advantage or private financial gain."
* When they distribute "1 or more copies or phonorecords of 1 or more copyrighted works" with a total value of greater than $1,000 within any 180-day period.
Criminal infringement is punishable by up to ten years in prison (for repeat offenders). See 18 U.S.C. § 2319.

#### Circumvention

The DMCA contains provisions to criminalize the circumvention of copy protection technology. See 17 U.S.C. § 1201 et seq. These provisions have been used to stop a variety of activities. The publishing of DVD decryption code was deemed illegal in Universal City Studios v. Corley, 273 F.3d 429 (2d Cir. 2001). Later, in U.S. v. Elcom, 203 F.Supp.2d 1111 (N.D. Cal. 2002), anticircumvention law was used to enjoin the publication of software that could convert copy-protected Adobe eBooks to unprotected PDF files.
One unintended consequence of the anticircumvention law was a flurry of litigation involving producers of after market accessories for electronic devices. Two cases decided in 2004 made it clear that the DMCA would not cover such anticircumvention claims. In Lexmark Intl. v. Static Control Components, 381 F.3d 1178 (6th Cir. 2004), anticircumvention protection was denied to a printer manufacturer after another company reverse engineered codes for its proprietary ink cartridges. In Chamberlain v. Skylink Technologies, 381 F.3d 1178 (Fed. Cir. 2004), the court ruled that buyers of garage doors were free to reverse engineer the code on their garage door opener, since otherwise they couldn't open their own garage.

#### Other offenses

* Publishing of a fraudulent copyright notice, or fraudulent removal of a copyright notice, is punishable by a fine of up to $2,500. 17 U.S.C. §§ 506(c)-(d).
* False representations in a copyright application are punishable by a fine of up to $2,500. 17 U.S.C. § 506(e).

### Defenses
#### Fair use

The most common defense to copyright infringement is fair use. It is a highly vague (and therefore highly versatile) doctrine. The Copyright Act provides (17 U.S.C. § 107) that a finding of fair use depends on:
* The "purpose and character of the use"—e.g., whether it is for profit or for educational purposes.
* The "nature of the copyrighted work."
* The "amount and substantiality of the portion used in relation to the copyrighted work as a whole."
* The "effect of the use upon the potential market for or value of the copyrighted work."
While all four factors must be considered, they are not exclusive: courts can (and do) consider other factors in ruling on whether use of a copyrighted work counts as fair use. Examples of fair use include:
* Parody, most likely to be found when the work is criticizing the original upon which it is based.
* Copying for personal use, such as the "time shifting" permitted by Sony, the "space shifting" permitted by Diamond and photocopying of books for research purposes. But if such copying is used to escape licensing provisions (as may be the case with software or technical journals), it may not be considered fair use.

#### License

A person may copy a copyrighted work if the original author has given them a license to do so. Licenses are often in writing, but they need not be: if the copyright owner gives verbal consent to another person, that person is legally entitled to copy the work to the extent allowed by the owner. Note, however, that transferring the entire copyright requires a written contract or deed.
More precisely, an exclusive license gives the "licensee" (the recipient of the license) the right to prevent others from using the work. An exclusive license must be in writing. A non-exclusive license allows the licensee to use the work, but does not give the licensee the power to grant or deny a license to anyone else. A non-exclusive license does not have to be in writing.

#### Copyright misuse

Copyright misuse is a fairly recent (and not universally accepted) doctrine that seeks to prohibit the use of copyrights for anti-competitive purposes. It is connected to antitrust law and derived in part from the patent misuse doctrine.

#### Statute of limitations

Under 17 U.S.C. § 507, a civil suit for copyright infringement can only be brought within three years "after the claim accrued." A claim accrues every time a work is illegally copied and every time an infringing work is illegally sold or transferred, so statute of limitations defenses are usually very difficult to successfully assert. Also under § 507, the statute of limitations in criminal cases is five years.

## Fair Use

Fair Use is the doctrine in American copyright law pertaining to the utilization of copyrighted works without the supposed necessity of economic reimbursement or artistic license. Because the application of this doctrine to cases of copyright infringement and utilization has rendered an exact definition of the doctrine elusive, law has been unable to reflect a statutory definition. The doctrine was finally recognized by statute in the Copyright Act of 1976, which was part of a greater general revision of American copyright laws.

### Fair Use According to Copyright Law

§107 in Title 17 of the United States Code consists of the fair use doctrine as recognized by statute:
Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include—
(1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
(2) the nature of the copyrighted work;
(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
(4) the effect of the use upon the potential market for or value of the copyrighted work.
The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.