Unlike a modern state, in a libertarian society, it is impermissible to detain suspects, intrude into private life through surveillance, compel testimony through the threat of violence, or forbid perjury. How then is the non-aggression principle to be applied without all these extremely useful tools necessary for an investigation? After all, without them, it is simply impossible to catch anyone, which means that instead of non-aggression, we will face impunity for a violent criminal who was not killed in self-defense.

anonymous question

Not everything is so bleak)

Surveillance

Surveillance and uncovering secrets of private life do not violate the non-aggression principle at all, so under ancap conditions, this direction will face even fewer obstacles than under a state. We should all mentally prepare to live in a condition of a 24/7 stream of everyone and everything in the public domain. It is already almost like this now, and the trend will only develop.

Compelling testimony

As usual, the state’s stick will be replaced by the ancap carrot. Yes, a person has the right not to share information with anyone, but if they are materially interested, the probability of evidence appearing increases. Even now, it is not perceived as something extraordinary when someone interested in an investigation announces a reward for testimony. As for compelling testimony against oneself, this is forbidden even under a state, although we all know how tenderly state representatives treat such prohibitions.

Detention of suspects

The more developed surveillance technologies are, the less need there is to detain a suspect. Simply put, retrospective research through open sources—what the suspect was doing at the moment in question—will finally replace interrogations and confrontations.

Actually, it is strange that this question concerns you so much: we are currently literally watching in real-time the investigation of numerous crimes committed by Russian officials, military personnel, and intelligence officers through open sources. In effect, almost everything here is as it is under ancap: you cannot detain, you cannot compel testimony, but it is quite realistic to study the matter. As for how the transition from investigation to court, or directly to sanctions, occurs under ancap, I have already written multiple times.