Dissent
The dissenting justices said that dogs should not be seen as a specialized tool because they are generally used by the public. Dogs only discover the smell of an illegal substance and do not reveal any private information, like the thermal imaging device in Kyllo. The dissenting justices also say that there was no reasonable expectation of privacy here, as it is not reasonable to expect that the odor of marijuana will never be smelled by a human outside your home.
The dissenters also strongly disagree with the idea of calling this a trespass. They say that approaching the front entrance used by all visitors and observing for one to two minutes (as the officers did here) does not violate the normal amount of time and space that a visitor is allowed.