I thought that I had remember where I saw it, but I couldn't find it. I did find this.
18. I recently purchased a double-edged survival knife. Does Michigan law allow me to carry this in my vehicle?
MCL 750.227 No. A double-edged cutting instrument, no matter what the length, cannot be carried concealed on or about a person, or whether concealed or otherwise in any vehicle operated or occupied by the person.
here:
www.michigan.gov/msp/0,1607,7-123-1591_3503_4654-10953--,00.htmlThe rule of thumb that I've always followed is that you should be able to close your hand over the knife blade.
Personally, I used to carry an Emerson CQC-7, but the combination of my dad giving me a small CRKT folder and reading that Ernst had said that he thought that the -7 was too large for it's intended purpose, I switched to the smaller knife.
What I've learned talking to people is that if the officer considers it a concealed weapon, it's a concealed weapon until proven otherwise.
Lastly, when I get around to jumping through the hoops for my CCW, this is definitely one question on my list.