From National Flag of the United States, 34 U.S. Op. Atty. Gen. 483 (May 15, 1925) (emphasis added):

I am in receipt of a letter from the late President Harding, dated February 15, 1923, requesting from my predecessor then in office an opinion defining precisely what is the National Flag of the United States, and what official action is proper in order to preserve the flag from desecration. Accompanying this letter is a petition from officers of the Military Order of the Loyal Legion requesting the President to obtain such an opinion….

From the correspondence attached to the letter of President Harding, above mentioned, it would seem that doubts have been expressed in some quarters as to the propriety of attaching a fringe of yellow silk to the colors and standards used by troops in the field. The use of such a fringe is prescribed in current Army Regulations, No. 260–10. In a circular dated March 28, 1924, The Adjutant General of the Army thus refers to the matter of the fringe:

‘For a number of years there has been prescribed in Army Regulations a knotted fringe of yellow silk on the national standards of mounted regiments and on the national colors of unmounted regiments. The War Department, however, knows of no law which either requires or prohibits the placing of a fringe on the flag of the United States. No Act of Congress or Executive order has been found bearing on the question. In flag manufacture a fringe is not considered to be a part of the flag, and it is without heraldic significance. In the common use of the word it is a fringe and not a border. Ancient custom sanctions the use of fringe on the regimental colors and standards, but there seems to be no good reason or precedent for its use on other flags.’

With these conclusions of The Adjutant General I am inclined to agree. The fringe does not appear to be regarded as an integral part of the flag, and its presence can not be said to constitute an unauthorized addition to the design prescribed by statute. An external fringe is to be distinguished from letters, words, or emblematic designs printed or superimposed upon the body of the flag itself. Under the law such additions might be open to objection as unauthorized; but the same is not necessarily true of the fringe.

The presence, therefore, of a fringe on military colors and standards does not violate any existing Act of Congress. Its use or disuse is a matter of practical policy, to be determined, in the absence of statute, by the Commander in Chief. If a fringe is used, its color and size are matters of detail which may be determined by the same authority. In the present state of the law, I see no reason for supposing that the paragraphs of the Army Regulations above mentioned are ultra vires, or that the statute imperatively requires the removal of fringes from all standards or colors. Conversely, if it should be decided by the Commander in Chief that the removal of fringes is desirable, there is nothing in the law which imperatively requires their retention.

Now some people have argued that this historical use of the fringe by the military means that the presence of the fringe makes the flag a military flag, and thus strips a civilian courtroom of authority to render decisions under regular non-military law. But the attorney general’s opinion reflects, I think, a much simpler principle: The fringe just doesn’t matter. It’s not part of the flag; it’s just a fringe. A simple point, though it seemed to call for an opinion signed by the Attorney General of the United States.