Clinton came to visit the preschool my SIL works at, the SS, LAPD and other law agencies heavily screened the people that work there.
The gen public who get tickets or are part of the audience have a cursory screening done as part of their admission to the event. There is no way to possibly screen out people who are there to disrupt an event.
Barring goofballs who are dressed in pink- the Code Pink buffons and searching people for hidden signs, shirts with anti war slogans or an idea that they are going to disrupt or try to shout down any one making a speech is patently un-American - and does infringe on their right of free speech, But I think asking them to be respectful to others that are part or being honored at a ceremony or graduation is a matter of common sense.
There is a certain lack of respect for decorum for their fellow man - some protestors think they are entitled to wrecking the day for the rest of us...It's not a right, it's a show of ignorance.
If I went to an antiwar demostration and began to shout down a speaker I can guarantee you that some 'peaceniks' would have no problem kicking the shiat outta me-the same people who profess to believe in the "Love, Not War" attitude.
I am not a religious person, but would never think of crashing a Sunday mass because I think that abortion is O.K. or I agree with same sex marriages.
In San Francisco a church service was crashed by some knuckleheads dressed as nuns because of some stupid religious rule.
I am more apt to listen to an opinion or cause when it's presented in a way that doesn't verge on hysteria or ruin any meeting, ceremony or gathering.
More often than not people look, point and laugh at who these people are.
Check out the news programs. I'll give you the standard report.
"Protestors were escorted from the citizenship ceremony that GWB spoke at today."
Nothing about their stand, exactly what they were protesting about or what their views are/were.
It had all the impact of passing gas in a crowd.
Some people noticed, some wrinkled their noses and some just ignored the whole incident- and in the end, the smell faded into thin air.