I don't know what it would be, I was a business major, maybe some sort of rubber under-suit or something that would ground the charge before it reached the target.
I imagine the person that comes up with such an invention would make millions from the liberal activist, student protester, general malcontent crowd. Of course then the police would just fall back to pepper spray, or the old tried and true billy club, but don't tell that to the protesters.
Light chain mail would work by preventing skin penetration and shorting out the electricity. But, chain mail isn't the lightest, most comfortable thing to wear, and it probably makes a weird clinking sound as you move.