Yep. This is actually very similar to what colleges have been trying to figure out with consent (see California's "affirmative consent"). Basically, according to Cal, if you do not acquire verbal consent at each portion of the encounter you're a rapist; i.e. "is it alright if I kiss you?" "can I eat you out?" "Is thrusting alright?" etc. What pair of drunken college students (this is what that statute is aimed at) are going to be comfortable enough to be that vocal during such an encounter?
A tongue in cheek solution:
The engineer’s solution:
Everyone who participates in the regulated activity needs to purchase a simple push-button device which controls a separate panel with a red light and a green light. During the regulated activity, each participant must hold down the button on the controller that illuminates the green light, which shall remain visible to the other party(ies) at all times. If, at any time, a participant releases this button, the green light goes off, and a red light comes on. Optionally, a siren could start to sound, to summon outside assistance.
These days, with Wifi and Bluetooth, I bet you could make the controller wireless and small enough to easily hold in one hand, leaving the other hand free for other activites…
I bet the Chinese could get something set up in a few weeks, and have it in stores by Xmas!
Failure to use such a device is cause to dismiss later allegations that consent was not given.
Batteries not included.
http://overlawyered.com/2014/10/california-sex-consent-law-engineers-solution/
Another solution that I think is both comical -- in that it completely removes all romance/sexiness out of the situation -- is walking around with a written contract of intent/consent. Make the chick/dude sign it and you're on your way to happy town.