Assuming #12 wire is being used, can one use 15 Amp snap switches on 20 Amp circuits assuming the load is less than 1440 Watts?
(80% of 15A @ 120V)

I don't like using #14 wire and I've always protected lighting circuits at 15A anyway; so can I put 20 Amp breakers in instead and still be code?

380-14a seems to point towards sizing for load rather than circuit protection...

But there's always a paragraph hiding in this book somewhere...

Yes, you can put 15 amp switches on a 20 amp circuit, provided the load does not exceed 15 amps.

There is no reason that I know, other than controlling a motor, to "Derate" your switch to 80% (12 amps).

'66,

Yes you can use 15 amp switches. I am kind of opposite in that I would prefer #14 on these 15 amp switches. It seems to me that getting the screw torque just right on (standard grade) 15 amp switches is tough. It's easy to overtighten and strip out the screws or if it's not tight enough you can watch the screws turn (loosen) as you push the device back into the box. I think 20 amp rated switches are a better match for #12 awg wire.

Bill

Never had that problem with Leviton or Eagle brand devices...except for that time I used my DeWalt screw gun...live and learn!