When is it appropriate to salute indoors?

Marines do not render a salute unless wearing a cover. Marines don't wear a cover indoors unless under arms. Marines not covered will be a the POA during colors/anthems, in or out of uniform. No hand over heart. Pretty simple really.

This Marines was not under arms, so should have been uncovered, at the POA. If he was just going along wearing a cover, he should have saluted.

Now, in order to not cause embarrassment or to promote combined/joint values, we do sometimes break our rules. For instance, I have saluted indoors without cover at a RoK NDU graduation, and I have saluted the sentries/guards in civvies at Fort Bragg (just so that the Army won't think Marine officers are complete douche bags. Partial, yes, but not complete!)

Having said that, I absolutely, positively, without apologies or embarrassment refuse to come to the POA and salute reveille (and even less if I'm in PT gear) gear like they do at Bragg. No way in hell I am saluting a wake up call!

Can't address what the USMC does, but in the Army See Appendix A-Saluting in FM 3-21.5(formerly FM 22-5) Drill and Ceremony. It is easier to read than the AR.

I'm off the impression if you wear your cover, it's a salute setting. However, you wear your cover when appropriate, and unless under arms, you don't wear your cover. Yes, a few exceptions. Dining facility, and the sort where policy applies. A potentially gray area for sure, but if it was prudent to wear cover, it was prudent was probably prudent to salute.

Ok, could you say that the White Belt (Or a white cartridge belt) would be under arms, while doing fire watch though out all the time I was in the Corp was considered being under arms even though I was not carrying a weapon. On the 200 anniversary I was part of the honor guard presenting the colors, if I remember correctly we wore white cartridge belts. Our covers we're also secured with the chin strap.

I watched this live on TV and raised the question to my buddies. The picture was taken at the Dallas stars hockey game the other day. For those mentioning the flag is behind him, that is simply a display on the jumbotron. He is in fact facing the flag. I thought it was different to place his hand over his heart rather than salute but like many others have stated probably doing what he was told.

I would have saluted, because I was covered. But, that is my judgement, based on my experience.

If your cover is on, then salute. Thus, he was in the wrong for wearing his cover or wrong for not saluting. As Marines see this, he was wrong. Staged or not, he should have known better. Army regulations do not apply to Marines. Our tradition can not be degrated because of public opinion. Semper Fi.

That is a interesting question. The picture raises some questions. Most events I have been indoors where you normally remove the head gear unless we were on duty ( like at the Embassy ). I also been told that you salute the flag and put your hand over your heart for the song. It appears that the flag is behind him. None the less I applaud his open show of patriotism and wouldn't put to much on the details considering the moment.

there is an old proverb: 'Whenever in doubt, salute"
with regard to this picture, since the Marine was in uniform and wearing his cover, the answer is yes, but with the standard military salute -the hand in heart is for civilians-
to simplify the issue, a change to protocol now allows all military personnel, active or retired, in uniform or in civies to render the military "hand salute" whenever it is appropriate: the national anthem, rendering honor to the flag, etc. The main point of this change is to enhance the pride of military service and to distinguish those who serve or served from those who did not.

This is a Marine. Army regulations don't apply. I worked with and trained with Marines. They don't salute in doors and don't wear head gear indoors except while under arms. This Marine was indoors and didn't render a hand salute but did the next best thing by placing his hand over his heart.
Even though we are all in the US military each branch has their own quirks. Head gear and saluting are just a few. Have you ever noticed how Marines at the White House or Embassies stand "At Ease"?Their hands are in the front not behind them.