This information is for general guidance and is NOT legal advice
Strong Licences and Internal Distribution
A question commonly asked is whether a larger work, which incorporates a strongly licensed third-party work, must have its source code made publically available. In the case of a larger work subject to the GNU General Public License 3.0, if it is kept private or distributed internally (i.e. it is only distributed within the company and staff do not have permission to distribute it outside of the company) then the company is only making copies for itself and it does not need to extend access to the source code beyond its own confines. However, once it is distributed to other organizations or individuals then the rights provided by copyleft must be passed on to them.
Remote Usage Provisions
Some strong third-party licences, most notably the GNU Affero General Public License 3.0, have additional provisions that explicitly extend copyleft to any individuals who make use of licensed works over a network (e.g. as web applications). In some special cases, such provisions are also implicit to the GNU General Public License 3.0. Again, when access is kept private or only provided internally, then it is regarded as internal distribution and there is no obligation to provide access to the source code. However, the risk of non-compliance is greatly increased if the licensed work (or a derivative of it) is ever likely to be used externally. This risk is compounded in agile development environments where software components are generally regarded as reusable in any larger work , including those to be made externally available.
Common Non-FOSS licences
- Code Project Open License
- Creative Commons Attribution 3.0 Unported License
- Creative Commons Attribution-Share Alike 3.0 Unported License
- and Public Domain
In situations where the nature of a third-party licence is unclear, this does not absolve a developer of responsibility for determining the conditions of use. Since copyright is an automatic and enforceable right for an author of a qualifying work, in all cases the initial assumption should be that such third-party works are not available for use in larger works until it can be confirmed otherwise.
Third-Party Licence Compatibility
Finally, when using a combination of components or libraries, with different third-party licences, it should be confirmed whether their terms and conditions are mutually compatible. This tends to be more of an issue with strong third-party licences licences, which require that all source code for the larger work be covered by the same license. For example:
- Neither the GNU General Public License 3.0 nor the GNU Affero General Public License 3.0 can be used in conjunction with any other licences (apart from each other)
- In some cases the GNU General Public License 2.0 may or may not be compatible with later versions of itself
In cases where two or more components or libraries are licensed under mutually incompatible third-party licences, then they cannot be used together as part of a larger work. This relates specifically to the issue of resolving multiple third-party licences that have been combined into the same larger work, and not the common practice of multi-licensing, where software is made available under two or more different licences, and recipients can choose the licence under which they would prefer to use it.