If I were a lawyer defending the cops, you betcha I'd be fighting her already! I'd certainly make sure that the knife doesn't get "lost" before an adequate forensic examination. (Reading the text of the Baltimore knife law, I think the knife on my keychain could be proven to be illegal.)
Mosby is an elected official, elected by Baltimore City voters, not statewide voters, in spite of the title. (She ran unopposed in the general election, but still only won 94% of the vote.) At best, she's used to sparring with underpaid and overworked legal aid attorneys, not experienced criminal defense attorneys who earn four times as much as she does.
I can see tons of civil liability by the City of Baltimore in this case. Criminal? We'll see.
I don’t disagree with much you said there, I do want to point out that the filing is from a “Baltimore Police Officer” not a defense attorney. So I was addressing the former, not the latter.
And if the knife gets lost along the way, which is more likely a BPD problem since they have probably been in custody with the evidence, reasonable doubt about the validity of the arrest is okay and they would get off. But they’re still going to pay a price for causing the death of Freddie Gray.