The latest move in the Philippines’ increasingly violent war on drugs under President Rodrigo Duterte, police are now going door-to-door in the poorest neighborhoods of the capital city of Manila, seeking urine samples and performing on-site drug tests.

This would be a major privacy concern anywhere in the world, but in the Philippines it’s another human rights disaster waiting to happen, as Duterte has been very public in his support of police summarily executing drug users, and publicly calling on the unemployed to “kill all the drug attacks.”

One of the districts, Payatas, is said to already have over 300 residents on a government “drug watch list.” These people are likely to be targeted particularly in these spot tests, and in the past, there’ve been claims that being on the list amounts to being marked for death at any rate.

Officials are playing up the idea that this is a “voluntary” test, though they are also implying those who refuse have something to hide, and presenting it as a necessary step toward a ‘drug-free” district.

Legal groups say they doubt that in practice the tests are really voluntary, and are warning they are flagrantly unconstitutional. Though there have been no specific reports of killings related to the testing yet, it has just started, and in the Philippines recently, one hasn’t had to wait long for any anti-drug program to turn into a slaughter.