There are so many angles to speak about on this issue. I struggled with what might be the best way to make an appeal to all, in order to better understand what the flag controversy entails. And honestly I'm not sure.
To try and keep this short as possible, I'm going to sum up the issue at hand by saying that the biggest problem with the flag burning controversy (in general), is that people tend to react from emotion rather than intellect and maturity in regard to the matter.
Geez, imagine if everyone (a majority) did that in other areas of life everyday - like driving (road rage) or knee-jerk reacting to people at a customer service job. If everyone just reacted on emotion - we'd have an even far more violent society than we already do.
Anyhow, the bigger issue to recently surface is the claim by Trump that he'd like to control how American Citizens think about and act toward something (in this case - the flag of course). The implications of such a mentality should overwhelmingly disturb everyone.
I'd like to share a couple things from prominent others to maybe help broaden the legal understanding on the issue. Despite the misunderstanding of the multitude - not only is it not illegal to burn the flag, but it is Constitutionally protected for anyone who chooses to do so. I'm not going to go in depth on citing case law, etc, but the Supreme Court has continually ruled against there being any penalty against exercising what has been declared a First Amendment Freedom of Speech expression. One of the most recent (to my knowledge) attempts to amend the Constitution on this matter, occurred in 2003. It was called H.J. Res. 4. It too was struck down. Those who argued against it summarized:
"If we adopt H.J. Res. 4, we will be denigrating the vision of Madison and Jefferson. If we tamper with our Constitution, we will have turned the flag, an emblem of unity and freedom, into a symbol of intolerance. We will not go on record as supporting a proposal which will do what no foreign power and no flag burner has been able to do--limit the freedom of expression of the American people."
Also a brief article written by Ron Paul a few days ago on the latest Trump/flag fiasco: http://www.ronpaullibertyreport.com/archives/what-everyone-missed-at-the-flag-burning-circus
A quote from it that sums it up real well simply put, says: "Peace and the non-aggression principle are simple to comprehend. Live and let live. I keep my hands off of you and your stuff, and you keep your hands off me and my stuff."
In other words: So long as it's your flag (your property), do whatever you want with it, and allow others to do whatever they want with theirs as well. It's Individual choice.
One final respected individual's article (and video) on it, comes from former Judge, Andrew Napolitano here: http://www.foxnews.com/opinion/2016/12/01/judge-andrew-napolitano-is-flag-burning-really-protected-speech.html
In the article, Napolitano quotes former (now deceased) Supreme Court Judge, Antonin Scalia:
"Even though he personally condemned flag burning, the late Justice Antonin Scalia joined the majority in both cases and actively defended both decisions. At a public forum sponsored by Brooklyn Law School in 2015, I asked him how he would re-write the flag burning laws, if he could do so. He jumped at the opportunity to say that if he were the king, flag burners would go to jail. Yet, he hastened to remind his audience that he was not the king, that in America we don’t have a king, that there is no political orthodoxy here, and that the Constitution, which is the supreme law of the land, leaves freedom of expression to individual choices, not government mandates."