Isn´t that illegal? And really risky? Since if the sub really changer their mind he or she can go ahead and report you to the police.
Depending on where you live, almost everything BDSMers do is technically illegal. You cannot legally consent to being beaten. That's because you cannot consent to breaking the law, and the law says you can't beat people.
So if you consensually beat somebody, and they agree the entire time, and they have a safeword and don't use it, and they don't tell you to stop at all, and you think everything is good and nice... they can STILL go to the cops afterwards and press charges against you.
If they have bruises or any other kind of mark, you're going to get convicted. Period. No matter how many time you say it was consensual.
As a Top, any time you play with anybody, you run the risk that they'll go to the cops afterwards. Usually, when you play with safewords, the -slim- line of protection you use against that risk is the fact that the bottom can always say 'stop', so you usually can count on the fact that as long as they don't say 'stop', they still like what you're doing. Though this doesn't always work out, because there's been bottoms who have accused Tops of consent violations after scenes where the bottom neither said stop, nor no, nor safeworded, nor gave ANY indication whatsoever that they wanted to stop.
If that happens to you as a Top, you're pretty much screwed, because nobody will believe you, and everybody will take the bottom's side.
When you engage in consensual nonconsent play, your risk goes up, because now you don't only have the situation where, if the bottom after play goes to the cops you're screwed, you also have the type of play going on where you know for sure that the bottom WILL say during the scene that they want to stop. They will safeword, they will yell 'no', they will beg you to stop, they will threaten you, they will plead. And despite all that, you continue, because they promised, before the scene, that even if they wanted you to stop during the scene, they would be okay with you not stopping once they cooled down after the scene was over.
So you're basically counting on the promise they made before the scene that they won't go to the cops after the scene, even though you'll on purpose violate their consent during the scene (because they want their consent to be violated during the scene, and consented to you violating their consent mid-scene, hence consensual nonconsent).
Can you trust their promise that they won't go to the cops after the scene?
Maybe... maybe not. But that's really a risk you're taking any time you play with anybody.
Even so, it's best to not engage in CNC with somebody unless you know them really well, and even then, it's best to start slowly and build up to more drastic scenes over a period of a few months.
I can be your whore
I am the dirt you created
I am your sinner
And your whore
But let me tell you something baby
You love me for everything you hate me for