When Dusty, a 19-month-old black Labrador, walked past a pipe full of marijuana during a recent police search of a house, he was doing exactly what his handler hoped.

The newest drug-sniffing dog on the police force in Bremerton, near Seattle, is one of a few police dogs in Washington state that are not trained to point out pot during searches. Other police departments are considering or in the midst of re-training their dogs to ignore pot as well, part of the new reality in a state where voters last fall legalized marijuana use.

"We wanted to train our dog on what was truly illegal substances, that would be heroin, methamphetamine and cocaine," said Dusty's handler, Officer Duke Roessel, who added that Dusty nabbed five pounds of meth during that recent search.

Police departments in Bremerton, Bellevue and Seattle, as well as the Washington State Patrol, have either put the dogs through pot desensitization training or plan not to train them for marijuana detection.

The law decriminalized possession of up to an ounce of the drug for individuals over 21 years old. It also barred the distribution and growth of marijuana outside the state-approved system.

Police say that having a K-9 unit that doesn't alert to pot will lessen challenges to obtaining search warrants because the dog won't be pointing out possible legal amounts of the drug. Traditionally, dogs are trained to alert on the smell of marijuana, heroin, crack cocaine, methamphetamine and cocaine. They can't tell which one it is or how much of each there is.

In December, the Washington Association of Prosecuting Attorneys told officers in a guidance memo that dogs that alert on pot face limitations when a search warrant is sought but those are "not fatal to a determination of probable cause."

The group instructed officers to point out that the dog was trained to smell pot and how that is relevant to other information when they seek a warrant, and that a "narcotics-trained canine's alert will still be relevant to the probable cause equation."

In Pierce County, however, prosecutor Mark Lindquist said authorities are being cautious about the new law because judges might excise the dog sniff from their analysis of probable cause. He's also not convinced dogs can be re-trained. "We'll need new dogs to alert on substances that are illegal," he said.

In January, the Washington State Criminal Justice Training Commission removed detecting marijuana from its canine team certification standards. The change doesn't prohibit trainers from doing so, but it's not required anymore.

But some police departments aren't making any changes. And some observers say that a state Supreme Court decision in 2010 in which the justices sided against medical marijuana patients who argued police officers no longer had probable cause to immediately arrest or investigate due to the legalization of medical pot.

Last fall's legalization law "just made one ounce not a crime for adults. That means that any amount over an ounce is still illegal, growing marijuana is still illegal, selling marijuana is still illegal, passing a joint to somebody is still illegal," said medical marijuana advocate and attorney Douglas Hiatt.

For different reasons, dog trainer Fred Helfers of the Pacific Northwest Detection Dog Association agreed with Hiatt.

But having spent 20 years as a narcotics investigator, Helfers said departments who abandoned pot training are having a "knee-jerk" reaction. He said they may miss actual crimes being committed. "What about trafficking? What about people who have more than an ounce?" he said.

Nonetheless, Helfers is helping departments who want to go through the "extinction" training, which he said is a common method to change what substances dogs alert to. It takes about an initial 30 days plus every day reinforcements to modify the dog's behavior.

"Overall, I think there's still a large amount of agencies on a wait-and-see approach with their dogs," Helfers said.