An implied license is an unwritten license

License

The verb license or grant licence means to give permission. The noun license or licence refers to that permission as well as to the document recording that permission.A license may be granted by a party to another party as an element of an agreement...

 which permits a party (the licensee) to do something that would normally require the express permission of another party (the licensor). Implied licenses may arise by operation of law

Operation of law

The phrase "by operation of law" is a legal term that indicates that a right or liability has been created for a party, irrespective of the intent of that party, because it is dictated by existing legal principles. For example, if a person dies without a will, his heirs are determined by operation...

 from actions by the licensor which lead the licensee to believe that it has the necessary permission.

Implied licenses often arise where the licensee has purchased a physical embodiment of some intellectual property

Intellectual property

Intellectual property is a term referring to a number of distinct types of creations of the mind for which a set of exclusive rights are recognized—and the corresponding fields of law...

 belonging to the licensor, or has paid for its creation, but has not obtained permission to use the intellectual property.

Examples

• A person who purchases a record album does not explicitly purchase a right to perform that album by playing it on a record player, but this right is implied.
• A person who posts a lengthy comment to an internet forum
  Internet forum
  An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages. They differ from chat rooms in that messages are at least temporarily archived...
  
   may claim copyright to that post. However, if posters in that forum commonly copy the entire text to which they are responding into a later post, the original poster will be deemed to have given an implied license for his text to be copied into the later post.
• In a non-IP context, a person who holds a party on their house gives all of the invited guests an implied license to enter their property, and to enter those parts of the property that would usually be made available to guests, such as the bathrooms.
• Where an employee invents something while on company time, the employer receives an implied license to use the invention, even if no contract
  Contract
  A contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...
  
   exists to assign rights to the employer. This is sometimes referred to as shop right.
• Where a copyright
  Copyright
  Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
  
  ed work has been commissioned, the law in the United Kingdom is that the creator retains rights in the commissioned work. Unauthorised use of the work would therefore infringe the creator's copyright. Nevertheless, the commissioner may have an implied license to use the commissioned work, although only for the particular purpose under which the commission was originally agreed.

Implication: from surrounding circumstances or by operation of law?

In the United States, implied licenses are usually considered to be of two kinds: either they reflect the intention of the parties, which is inferred from a fact-specific inquiry into the surrounding circumstances, or else they are constructive agreements, in which case the intention of the parties is likely to be immaterial. In reality, there is a continuum between these kinds of implied license and it may be difficult to determine whether the license or contract in question is one which the law implies, irrespective of any protests by the unwilling licensor, or instead one inferred from the whole pattern of factual circumstances including the evidence of intent.

In England, there is more of a tendency to regard all implied licenses as matters of fact and intent, while what would be a license implied by law in the US is treated under some other branch of substantive law such as the doctrine of non-derogation from grants

Doctrine of non-derogation from grants

The doctrine of non-derogation from grants is a principle of the law of England and Wales. As the House of Lords explained in British Leyland Motor Corp. v...

.

In both countries, the exhaustion doctrine has the effect of creating an implied license to use a product sold under the "authority" of the patentee. It is controversial whether and to what extent contractual expedients can successfully limit the scope of such implied licenses.

Express license

The opposite of an implied license is an express license, which must be in writing, for some forms of intellectual property. Oral exclusive licenses were permitted, however, under US copyright law before 1978. Oral nonexclusive copyright licenses remain valid under US law. Patent licenses may be oral. Licenses under the Semiconductor Chip Protection Act must be in writing.

Further reading

• Kenneth L. Port et al., Licensing Intellectual Property In The Information Age (2005), p.338-355.