Free Speech: Public Forums and Non-Public Forums
When analyzing free speech First Amendment issues, courts typically distinguish between different types of fora.
The public forum, such as a park, street, or sidewalk, is where people traditionally express their views. The government can usually not restrict someone from expressing his opinion in a public forum unless the government has a critical purpose to do so and adopts the most narrow measures possible to achieve that goal.
In contrast, a non-public forum is a place where people normally do not go to protest, assemble, and express their views. For example, an office building or a school is not a public forum. The government can impose reasonable restrictions on expression in a non-public forum. For example, the government can prevent someone from marching through a public school expressing his views because the school could not function under those circumstances.
The Limited Public Forum
In some cases, the government changes non-public forum into a forum where people are authorized to express themselves in a certain way or on a certain topic. For example, the government could create a space on city grounds normally reserved for art and invite people to come and share their opinions on a public topic. In so doing, the government has transformed the non-public forum that was reserved for art displays into a limited public forum devoted to a particular topic. Now, the government cannot restrict someone from expressing his opinion within the limited public forum.