Can a kinged piece jump another king?
As was indicated by @JaysonSmith, a king can always be jumped by another king. This holds for any variant of draughts/checkers.

The privileges that a king obtains differ by variant, however.


backward movement: in all variants, kings can move backward, but men cannot.
backward capture: in all variants, kings can jump backward, but men cannot for American/English checkers/draughts, Italian, Spanish, Czech and Thai draughts.
long range movement and capture: a king can move and capture long ranged (like a bishop in chess) for International, Frisian, Russian, Spanish, Czech and Thai draughts, as well as for Pool checkers, whereas men are short ranged in all variants.
invulnerable being captured by men: a king cannot be jumped by men in Italian draughts.