While your class readings make reference to very famous and specific court decisions, there are others that may have relevance to your side of the debate.
Freedom of Speech -- This is the link to the Wikipedia page and it is perfectly acceptable to use the openly editable free content source as a starting point. You can easily confirm that the information is correct by using the external links and references on the page.
The Supreme Court site does offer access to opinions, court orders, speeches and questions presented. Everything is straight from the Justice's writings and will be written with legal vocabulary.
SCOTUS Blog gives a more understandable description of the issues and rulings. The information will be written with an emphasis on plain English and simple meanings.
Article Three of the Constitution establishes the Judicial branch of our government. The Supreme Court is the top court for all the land.