https://reason.com/volokh/2018/06/18/il ... n-on-carry
In arguing to the contrary, the State cites Heller, in which the Supreme Court stated that nothing in its opinion "should be taken to cast doubt on ... laws forbidding the carrying of firearms in sensitive places such as schools and government buildings," which it described as "presumptively lawful." But the State conflates regulations banning the carriage of weapons in certain sensitive places (e.g., schools and government buildings) with [the law involved here], which bans carriage near those places. This distinction is significant. A ban on firearms in specific places imposes less of a burden on the right to bear arms than one that extends to an area of approximately three city blocks around those same places. While a gun owner can simply choose not to enter locations deemed sensitive, it is manifestly more difficult to avoid areas within 1000 feet of those locations, particularly given that there is no notification where the restriction zone begins or ends. Indeed, the ban at issue here, just as the ban 1000 feet around public parks at issue in Chairez, effectively operates as a total ban on the carriage of weapons for self-defense outside the home in Chicago. As such, it runs afoul of Aguilar, in which the supreme court held that the right to carry firearms is particularly important when traveling outside the home.
For these reasons, we conclude that [the statutes] prohibiting possession of a firearm within 1000 feet of a school are facially unconstitutional....
Nonetheless, the court criticizes the new Illinois law that allows carrying by concealed carry license holders near a school (the law was enacted after the events in this case), and seems to suggest that a narrower zone around schools in which guns are forbidden—perhaps focused "on public ways adjacent to school property"—may be both wise and constitutional:
Our holding today is narrow in that it addresses only the pre-2015 version of the UUW statute. The current version of the statute excepts from its reach those who have a valid license under the Firearm Concealed Carry Act. Significantly, the Firearm Concealed Carry Act continues to prohibit the possession of firearms in "[a]ny building, real property, and parking area under the control of a public or private elementary or secondary school," even for those with valid licenses.