Featherstone testified that he has been involved in hundreds of arrests, about 30%-40% of them involving backpacks or bags, and that "every one of them resulted in a search."
When prosecutor Zachary Kaplan asked how many of those searches involved a warrant, Featherstone said none that he recalled.
The defense has argued the officers violated Mangione's constitutional rights against illegal search and seizure because they lacked a warrant when they searched his backpack.
"It must be legal, I do it all the time." This is not the compelling argument they think it is. Or at least, it wouldn't be if we actually had the rule of law.
Edit: Also the fourth amendment is protection against unreasonable searches and seizure, not unusual searches and seizure. Just because they do it all the time doesn't make it actually reasonable.