WHAT'S MILES O'BRIEN'S RANK?

The Canon Answer:

Chief Petty Officer, firmly established in "Hippocratic Oath" (Bashir and O'Brien stranded on a Jem'Hadar infested planet--their leader addresses him specifically by rank).

BUT THE BIG QUESTION IS...

WASN'T O'BRIEN A LIEUTENANT? WHAT HAPPENED?

The Canon Answer:

Not given.

The Non-Canon Answer:

Yes, O'Brien wore lieutenants' pips early in the run of TNG, and was verbally referred to as a lieutenant by Riker in the TNG episode "Where Silence Has Lease." This fact is conveniently forgotten later on in the series, when he starts wearing a single black pip (presumably a petty officer's designation). How he became a noncommissioned officer, we can only speculate--but what muddies things up is that on DS9, O'Brien has dropped many strong hints that he never wanted to be an officer, and never attended Starfleet Academy. Off the top of my head, here are a couple of no-prize explanations:

• O'Brien was given a field commission early in TNG for reasons unrevealed--perhaps there was a staff shortage somewhere, maybe he went on a special mission. Once that stint was over, not wanting to be saddled with the hassles of being an officer, he elected to revert to his lower rank (like Riker must've done after "Best of Both Worlds II").
• The Petty Officer "pippage" used to look very similar to lieutenants' pips, so much that people like Riker could confuse the two easily. When the Pips and Rank Markings Department at Starfleet realized that people found it hard to tell lieutenants and petty officers apart at a glance, they revised the pip system and eventually designed the embroidered chevron O'Brien wore on DS9.

The Lowdown:

It's easy to see that O'Brien was a character that gradually grew into prominence--Colm Meaney was a nameless extra in "Farpoint," unless you call "Conn" a name. So, like "Bill" Riker, "Class of '78" Data, and other inconsistencies, this was one of those details that was meant to be swept under the rug and forgotten. Although his "demotion" appeared to come earlier, I recall reading somewhere that the main reason the writers busted O'Brien down a rank was so he would be compelled to follow Lt. Barclay's orders in "Realm of Fear."

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