"Sweat of the brow" is an intellectual property law doctrine, chiefly related to copyright law. According to this doctrine, an author gains rights through simple diligence during the creation of a work, such as a database, or a directory. Substantial creativity or "originality" is not required.
Under a "sweat of the brow" doctrine, the creator of a copyrighted work, even if it is completely unoriginal, is entitled to have his effort and expense protected, and no one else may use such a work without permission, but must instead recreate the work by independent research or effort. The classic example is a telephone directory. In a "sweat of the brow" jurisdiction, such a directory may not be copied, but instead a competitor must independently collect the information to issue a competing directory. The same rule generally applies to databases and lists of facts.
Civil law jurisdictions have traditionally used the similar but not identical concept of droit d'auteur. On a European level, some Guidelines of European Parliament tend to harmonize the protection of Intellectual Property throughout Europe and the doctrine gains more influence. A good example is the Databases Directive 96/9/EC - in this Directive, the member states of the EU are obliged to confer protection on non-original databases, that is on those that embody no creativity, but are a consequence of substantial investment (financial, labour etc.).
In a traditional English idiom, the sweat of one's brow refers to the effort expended in labor, and the value created thereby. The phrase is famously used in English translations of Genesis 3:19. The law doctrine takes its name from this idiom.
 By country
 US copyright law
The United States rejected this doctrine in the 1991 United States Supreme Court case Feist Publications v. Rural Telephone Service; up until then it had been upheld in a number of US copyright cases.
Under the Feist ruling in the US, mere collections of facts are considered unoriginal and thus not protected by copyright, no matter how much work went into collating them. The arrangement and presentation of a collection may be original, but not if it is "simple and obvious" such as a list in alphabetical or chronological order.
 UK copyright law
Under the Copyright, Designs and Patents Act 1988, for copyright to subsist in a work, that work must be original. However, courts have not adopted a literal reading of this requirement. For over a hundred years, English courts have held that a significant expenditure of labour is sufficient. The consequence of this is that if A makes a work, in which copyright subsists, and B subsequently adds his skill, judgement and labour, altering the form of A's work, B will potentially have a copyright in the work he produces. This suggests that copyright is not about protecting ideas, because one can acquire a copyright by expending skill, labour, and judgement, but no creativity or inventiveness.
In Walter v Lane (1900) (Pre-CDPA), reporters took shorthand notes of a speech, punctuated them, etc, and published them in the Times Newspaper. The court held that the reporters were authors of the published speech, and, as such, owned a copyright in the published speeches, because of the considerable skill, labour, and judgement they exercised. For the avoidance of doubt, whilst not considered in the case, the author of the speech would have also owned a copyright in the speech.
In University of London Press v University Tutorial Press, the question arose as to whether certain mathematics exam papers were original literary works. The exam papers just consisted of conventional maths problems in a conventional manner. The court held that originality does not mean that the work must be an expression of individual thought. The simple fact that the authors drew on a body of knowledge common to mathematicians did not compromise originality. The requirement of originality, it was held, does not require that expression be in an original or novel form. It does, however, require that the work not be copied from another work. It must originate from the author. As such, even though these were the same old maths problems every student is familiar with, and even though there was no creative input, the skill, labour, and judgement of the authors was sufficient to make the papers original literary works.
In Cummins v Bond, a psychic in a trance claimed to have written down what spirits told her, through a process of automatic writing. In court, she accepted that she was not the creative author of the writing. The creative input, had, presumably, come from the spirits. Nonetheless, the court held that she had exercised sufficient labour and skill in translating and transcribing what the spirits told her, so she had a copyright in the resulting literary work.
 See also