He is on probation for 4.5 yrs. For possession of a controlled substance. Its been 3 yrs ago now, he violated before for non report, but this time he has a new possession charge with obstruction, dui,no taillight, no license.. How much time can he be facing now?

There are multiple charges here... Driving without a valid license alone can get a year in jail on its own. I've seen a lot of people get that too.

DUI is another that can carry jail time on its own... plus the original time (back to square one on a parol violation)... whatever the possession charge might bring.

Personally if they tack on them one after the other and not make them concurrent as I hope they do... it can add up a lot more...

And they are not as nice for repeat offenders.

The no taillight is the least of his worries... thats a fine and little more.

Now of course exactly how much is determined by the courts... the Agents of the court... and local laws where this occurred. Without knowing all those all anyone can do is guess.