R v Ray - D in relationship with V former partner, feared use of a knife and fatally stabbed V.
1. whether degree of force is reasonable in circumstances D believed them to be
2. Householder not acted reasonably if force is grossly disproportionate
3. degree of force that went over the top would be considered grossly disproportionate
4. May or May not be regarded as acting reasonably if force was disproportionate