I'd agree with you much more if Manning hadn't already been tried and served time for the Wikileaks case.
I also think 18 months is far more punitive than coercive. If it was a month, which is a terribly long time to be confined in a cage, I'd find it more acceptable.
As it stands, 18 months is longer than many people serve for violent crimes. And this person already stood trial and was already imprisoned for this same case.
In terms of the guy sitting in jail for 3 years. I've heard of that. I strongly feel he should be released or tried on existing evidence (no need to violate the 5th). Two wrongs don't make a right.
The original comment we are answering seems to be correct:
> This shows the whole world how hopeless the US injustice system is. None of this would be possible in a civilized country.
Civilized being defined as the rule of law... it seems he is correct, as the proceedings against manning seem to violate the laws (both the 5th as well as double jeopardy)
Precedent, other things being worse... those don't address the original argument: this is America's barbarism. The example of the guy sitting in jail in-definitively seems to only support this perception, not detract from it. Of course, you are free to perceive it as you like. Some things we'll never agree on. :)