Where is this guaranteed to American citizens?

On May 4, 1970 students at Kent State University in Ohio protesting the American invasion of Cambodia were fired on by Ohio National Guardsmen. In all, 67 shots were fired, 4 students were killed, and 9 students were wounded. You will assume one of the following roles:

A student eyewitness at Kent State, writing to your parents about all you saw and heard.

or

An officer from the Ohio National Guard, 107th Armored Cavalry, who was present on campus writing a report to your superiors.

Briefly explain the circumstances leading to the confrontation between students and National Guardsmen, and explain what it felt like to be there when the shooting started.

Also, compare the Kent State Massacre to the Boston Massacre in 1770, in terms of the issues at stake, the actions that were taken, and the impact of this event on American public opinion. Finish your report/letter with a discussion of the right of people in the United States to peaceably assemble and protest the actions of their government. Where is this guaranteed to American citizens? Does this right have limits?

A note of caution: be sure to use standard, reliable sources (such as Wikipedia or the report of the Scranton Commission) in putting together your post. Double-check your sources for accuracy if you are in doubt. Remember, a historian deals with real facts, not speculation or conspiracy theories.