© Caching
Caching improves the efficiency of Web browsing by storing copies of Web pages and other downloaded information so that they can be easily retrieved without downloading the material again from the original source. There are two broad categories of caching--local caching and proxy caching:
- Local caching occurs in the user's own machine's random access memory (RAM) or the user's hard drive. This type of caching allows users to return to a page viewed earlier by clicking the "back" button on their browser and allows users to view a page offline. (You can control the amount of space on your local computer dedicated to caching through your browser options).
- Proxy caching occurs at a server other than the original source. (AOL, for example, often caches Web pages that are popular among their users.) This makes the page available to all their users without having to go back and download the page from the original source each time. Some search engines cache sites viewed by a "robot" so that they can be sure the page will be available for view by those using the search engine, even if the web page itself has been removed. The next time the robot "crawls" the Web again, the page is generally deleted.
There is a legal argument to be made that caching constitutes fair use or is permitted under an implied license.
When copyright holders post their works on the Internet, the theory goes, they subject that work to the technology that makes the Internet function efficiently for all users. However, the issue is not so simple, because the practice of caching can, potentially, have a negative impact on the rights of copyright owners. Problems that can arise include the following:
- Loss of control - When Web pages are cached, the creator of the page losses the ability to control what a user sees. Caching copies old versions of pages that may be updated or revised.
- Dated information - Caching can materially harm Web sites that have time sensitive information that is updated regularly.
- Incorrect user information - Caching limits the ability of Web site operators to monitor the use of their site. Among other things, this can hurt their ability to collect advertisement revenues.
- Unauthorized access - unauthorized parties may view material that is protected by password access if that material is cached on a proxy server.
The Digital Millennium Copyright Act attempts to resolve some of the problems posed by caching. ISPs are granted limited liability for activities, including caching material for later retrieval. The liability of an ISP for caching is limited as long as the ISP implements specific measures to refresh and protect copyrighted material.
Other countries have taken what some observers call "technology-neutral" approaches. Australia, for instance, has debated amending its Copyright Act of 1968 to make temporary reproductions of copyrighted material a non-infringing activity without implementing specific conditions that ISPs must adhere to. In effect, the Australian government is making copyright owners responsible for protecting their works from potentially harmful caching activities. For example, Web site creators are being advised to use code that places a "use-by" date on their pages that will automatically refresh an old cached page.
In 1997, the European Union (EU) introduced the Copyright Harmonization Directive that provides mandatory exemptions for caching and browsing. It allows these acts as long as they are "transient," "integral to delivery technologies," and have "no economic significance for rights holders." The EU E-Commerce Directive of 1998 provides ISPs additional safe harbors as long as they meet certain provisions. These provisions in fact are very similar to the conditions required under the DMCA.
