Have you considered adding dogs that can smell if you’re a downer?
If there are no dogs (of any kind), I would like an in story reason for it (for example dogs might have had a part in the Bad Thing that NEVER HAPPENED in Wellington Wells during WWII and as such all the dogs in Wellington Wells have been killed). If there are dogs, but they aren't used against downers, I would like an in story reason for that.
Possibilities to consider (if you do add dogs):
* If you are carrying joy (be it pill or joy laced food or water), but are a very sober, the dog assumes you are not a downer, because it is only smelling for the drug, not the chemicals the human body gives off when on joy.
* The dogs can used fairly passively, at entrances to restricted areas.
* They can be used to help policeman actively track down downers.
* How significant of a threat are they in combat (realistically, it would probably depend on the breed)?
* Ways to 'defeat’ dogs, perhaps inconspicuously, with items. For example, I read that the Danish resistance mixed cocaine and rabbits blood against the Nazi’s dogs, my understanding is the rabbit’s blood would encourage the dogs to smell the cocaine that was mixed into it (Dr. Ernst Trier Morch supposedly came up with the idea). The cocaine would then impair (at the very least, temporarily), the dog’s sense of smell, which made it less useful (and perhaps less than useless as it failed to provide the Nazi's the assistance they thought it was providing). IIRC the historical fiction book Number the Stars went as far as saying the sense of smell was temporarily “destroyed”. And of course there are less conspicuous was to defeat a dog.
* How would a dog react if a banger went off near it, even if the dog was completely unscathed? (hint, a dog could probably be trained to act different then give its impression of a pet dog on the 4th of july.)