Law / United States / 
Illinois
Illinois Computer Tampering, authorization tied to posted network terms
In force since .
A computer misuse rule binding public and private bodies.
- Audit expectation
- none
What it requires
- Complying with a site's posted terms and conditions for network access is what subsection (a-10) requires for guest or patron access to count as authorized in Illinois, so violating a public site's terms of use here can raise this statute, not only a private contract claim.
- Do not assume defeating a technical access control is required for exposure under section 17-51; the statute's own text reaches access in excess of the authority granted, independent of any circumvention.
These lines are LexLint's reading of the law's text.
Who enforces it
Settledness
- As of
- Open questions
- Does a website that serves its pages to any visitor mean that 'the owner authorizes the public to access the computer network' under 720 ILCS 5/17-51(a-10)(2)?
- Does a robots.txt directive or a terms-of-use clause count among the 'terms or conditions for use of the computer network that are imposed by the owner' under 720 ILCS 5/17-51(a-10)(2)?
- When a scraper does not comply with those terms, is its access 'without the authorization of a computer's owner' under subsection (a), or does it only lose the deeming rule in subsection (a-10)?
What it makes you log
Logging duty
Section 17-51 defines computer tampering as knowing access, access that obtains data or services, damage, program insertion or falsified e-mail routing information without the owner's authorization or in excess of the authority granted, deems access authorized where the owner opens the network to the public and the person complies with the owner's terms of use, and sets the sentences and civil remedies. It requires no log or record and carries no territorial clause.
- Kind
- None
- As of
What this law does
Section 17-51(a) provides that a person commits computer tampering when he or she knowingly and without the authorization of a computer's owner or in excess of the authority granted to him or her accesses a computer, network, program, or data, naming both the without authorization and in excess of authority granted prongs the Computer Fraud and Abuse Act (CFAA) is built on, unaffected in its Illinois application by Van Buren v. United States, which narrowed only the federal statute.
Distinctively, subsection (a-10) provides that accessing a computer network is deemed to be with the authorization of a computer's owner if the owner authorizes patrons, customers, or guests to access the computer network and the person accessing it is an authorized patron, customer, or guest and complies with all terms or conditions for use of the computer network that are imposed by the owner.
This textually ties authorization for guest or public access to compliance with the site owner's own posted terms and conditions, a more explicit authorization-follows-ToS link than a bare computer-misuse statute carries elsewhere, and means a scraper that violates a site's terms of use for public access may be reading itself out of the (a-10) safe harbor even absent any technical circumvention. No Illinois appellate decision applies this provision to scraping specifically.
When LexLint raises it
When your app profile says your app crawls the web.
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