[xinniethepooh]

Source on it being de-facto illegal?

I've not seen anything that says simply scanning for open ports is illegal, doing vulnerability scans may be though.

[xenadu02]

They mean a lot of ISPs and VPS providers will flag & terminate your account for launching port scans so it is difficult to find somewhere to run such a scan at any kind of speed.

[sneak]

No, I meant national police from several countries will investigate you.