Wikipedia says that in a police state, the government exerts an extreme amount of control over society and individuals. That leaves "extreme" undefined, though, so it's subjective. (Also, you know, Wikipedia.)
I'm not the one you asked, but: Me, personally, I'd draw the line at the independence of the courts. If the courts are independent, if they can rule against the police for failure to prove their case or for procedural violations or whatever, then it's not a police state. If the police win the borderline cases (or worse, the clearly bogus cases) just because they're the police, then it's a police state.
I'm not an expert, but I think it would probably start with funding. I think they're massively overworked, and as a result they do an inadequate job for each defendant.
I'm not the one you asked, but: Me, personally, I'd draw the line at the independence of the courts. If the courts are independent, if they can rule against the police for failure to prove their case or for procedural violations or whatever, then it's not a police state. If the police win the borderline cases (or worse, the clearly bogus cases) just because they're the police, then it's a police state.