In the UK, spanking or smacking is legal, but it must not cause an injury amounting to Actual Bodily Harm (a "serious" injury such as visible bruising, breaking of the whole skin etc.); in Scotland since October 2003 it has been illegal to use any implement or chastise to the head when disciplining a child. In England and Wales slippering (. striking the buttocks repeatedly with the sole of a slipper) has been the traditional method of punishing children in the home. It is assumed still to be legal, provided that no long-lasting bruises are caused.
If the slave is a heavy masochist, then something other than corporal punishment might be warranted. It goes without saying that punishment is not intended to be fun or provide pleasure. A slave should not be allowed to misbehave to fulfill her masochist needs and never rewarded for bad behavior. Don’t let what you intend to be a punishment be a reinforcement for bad behavior. Being placed behind the couch in the living room or den for an afternoon can teach her a valuable lesson. If she makes a noise or disrupts you in any way, her time behind the couch can be extended. The use of physical bondage is not necessary, using mental bondage by instructing her to remain quite, still and out of site. In general, the more she loves pain, the less it should be routinely applied as punishment and the more care it takes in administering pain as punishment.