This is a little off topic although still relevant, but I wrote piece in law school about how drug-detecting dogs need to stop being used to articulate probable cause to search, and I get mad whenever I about dogs being used like in the article. As you know, a warrant isn't required for a dog sniff search. SCOTUS's reasoning in U.S. v. Place was that 1) there's no reasonable expectation privacy in unlawful items, 2) dogs are highly accurate, and 3) dogs are trained to only alert to lawful items. Therefore, highly accurate dogs will only alert to unlawful items, thereby not invoking the Fourth Amendment and the warrant or probable cause requirements because of the minimally intrusive nature of the search. But, this logic couldn't be more wrong.

First, studies have consistently shown that dogs are not accurate, some even finding that dogs' alerts were wrong more often than right. There have been numerous instances where dogs have alerted the individuals who had recently handled food or touched another dog that was in estrus. To be fair, dogs themselves are mostly accurate, but handlers aren't, as they misinterpret non-alert behavior as an alert, they cue the dog to alert both intentionally and unintentionally, and sometimes they just use the dog as a license to search.

Second, just because a dog is accurate, he still may wrongly alert. A dog alerts to the scent of contraband, not the contraband itself. Image a pizza detecting dog. He would be trained to alert to the scent of pizza rather than the actual presence of pizza. In this respect, a dog can often alert to where contraband was once located, but is no longer present. This is important because of how frequently paper money is contaminated. As much as 80% of paper bill is contaminated with cocaine and/or methamphetamine. In fact, money contamination is so rampant that the DEA has stopped testing money for contamination during their investigations. So, a dog that alerts to contaminated money is accurate because he has alerted to the scent of contraband, but is nonetheless wrong because no actual contraband is present. Bear in mind, paper money is a lawful item, meaning that one would have a reasonably expectation of privacy. Simply put, if you have paper money in your pocket, there's a significant chance that a drug dog would alert if sniffing you.

So, here's my issue with Place and dogs being used without a warrant to establish probable cause. The Place court said that dogs are highly accurate, but his is plainly false. The Place court also reasoned that drug dogs only reveal unlawful items where there is no reasonable expectation of privacy, but this is also plainly false. So, the Fourth Amendment is clearly invoked by a dog sniff search because they aren't minimally intrusive like the Place court reasoned. Dog searches do reveal items in which individuals have a reasonable expectation of privacy, and dog searches simply are not accurate. So, long story short, officers shouldn't even be able to use drug dogs to articulate the probable cause needed to search these vehicles in the first place.

TL;DR Drug dog searches are wrong more than they're right, up to 80% of paper money is contaminated with narcotics, and (I think) warrantless dog searches violate the Fourth Amendment.