A question for the USA members of the forum.

Following the charging of Wang Wenyi for heckling the Chinese president, what rights does the first ammendment protect?

From BBC news:
"Her lawyer argued she was entitled to free speech under the First Amendment.

Prosecutors said the amendment did not allow her to break the law."

So why does the First Ammendement allow laws that restrict free speech, or am I missing something here?

BBC website for the full story