I've corresponded with the person the OP referred me to.
The gentleman ("Luke") tells me:
1. The instructor was relaying an experience his friend had with the City of Detroit PD.
2. The instructor made it clear that wasn't the law.
3. That Detroit PD doesn't seem to follow the law (or doesn't care).
4. The prosecuting authorities did not follow up on charges (sounds like the basis of a 42 USC 1983 case?)
From "Luke":
Hello Phillip,
Yes, everything said is correct. The words came from my instructor's mouth.
The discussion came up when the instructor was saying how he carries a backup, and one of the students asked if it was legal to carry two guns on your person. My instructor said that yes it is legal to do so, but be careful in Detroit. I know that principle of the law that if there is no law against something then it is legal, and the instructor knew that too. But, he said Detroit police look at the law backwards. They say that there is nothing in the law saying you can carry more than one gun on you so they arrest you. My instructor said he knows of this because of friends or acquaintances that have had problems with Detroit police.
My instructor said that when the people he knew would get pulled over that they would disclose they were carrying. The police would ask where they were carrying and the operators of the vehicle would say "here" and "here", and they would proceed to be arrested because they were carrying two guns. My instructor said the prosecutors haven't followed through on any charges because there is nothing to charge, but he said there must be someone up in the brass of the Detroit police telling them to do this.
He shared this just as a warning from his experiences. He had no reason to provide misinformation, and he was not trying to scare us.
I inquired further:
So he was relaying an experience rather than making a statement of what was legal/illegal?
"Luke" responded:
Yes, it was purely from experience and he said that. He knows the law and explained it, but he said Detroit police doesn't seem to follow this aspect of the law properly.
I don't think we can blame the instructor here for passing on bad information -- he was just relaying a story. From what I hear about Detroit PD, the story is believable, especially (but sadly) if the person they stopped was "brown". I've heard many in DPD are racist (even though many of them are "brown" themselves).