When, if ever, should the government be permitted to restrict free speech

Well this is a huge question, the government will probably have a hard time restricting all of the United States permission of "Free Speech", while they probably can in private property, and other private areas that civilians wish to pass through, they won't necessarily be able to restrict "Freedom of speech", unless it's threatening anyone or anything such as a business or a v.i.p.

One of the founding principles of the United States that Americans cherish is the right to freedom of speech. Enshrined in the First Amendment to the Constitution, freedom of speech grants all Americans the liberty to criticize the government and speak their minds without fear of being censored or persecuted.

Right?

Even though the concept of freedom of speech on its face seems quite simple, in reality there are complex lines that can be drawn around what kinds of speech are protected and in what setting.

for starters, there is the structural trend of rising primary government expenditure as a share of gdp, which reached 36% in 2014, up from 22% in 1991. this increase reflected a political desire to address the poverty and inequality that had gone unaddressed during previous decades. to support the increase, brazil’s government increased taxes on consumption and promoted progress toward labor-market formalization. nonetheless, public investment, particularly in infrastructure, took a hit. in fact, with the exception of the 2005-2008 period, total investment as a share of gdp has remained below 20% since 1991.

the answer is richard nixion