The only time it can be used as a counterspell is if the person playing the spell you wish to counter is non-active and you either have a higher XP than that person or if you are active.
Sorry but this is wrong.
The advanced rules wrote:
Because it is a cancel effect, [Counterspell] takes priority even when played by a non-active player.
Counterspell always come first, last in first out, then the active player's spells, then other players spells. You can couterspell Jeopardy.