I've always classified Person of Interest as sci-fi, however most sites (such as wikipedia) never mention this and just call it crime and/or drama. My opinion is based on the following in-universe facts:
- There are two AI computer systems which are powerful enough to monitor every camera, microphone, telephone, financial transaction, website and god know what else in the world.
- They both understand all languages flawlessly and can easily communicate with humans.
- At least one of them is shown to be more intelligent than its creator as well as the people who believed they "owned it" (it tricked a bunch of humans into moving it).
- At least one of them has their own agenda which isn't known to anyone.
Now I'm only a programmer, but I don't believe any of this is possible with our current technology, surely this means the show is sci-fi?