Originally Posted by Section 107

Understandable, because that was a typo; should have been "explosives and drugs" - I fixed it above.

Probable cause/reasonable suspicion is a complicated area of law which we shant get too much into here but when a canine indicates for explosives, the indication is accepted as a justification of reasonable suspicion and additional investigation.
Except in rare situations, the officer that is the dogs handler will not be the officer that conducts any subsequent search.