You've got to have probable cause or a warrant before you rip open a teddy bear. Even if the teddy bear is mailed using a fake name and return address. And even if the teddy bear subsequently turns out to contain a half-pound of marijuana.
That's the law, at least now, here in California. And in the Seventh Circuit. Though it's not the law in the Northern District of New York.
Teddy bears throughout the Golden State rejoice.