Defence

lf the nature of the assault is such as to cause reasonable apprehension of death or grievous harm, and the person using force by way of defence believes on reasonable ground that he cannot otherwise preserve the person defended from death or grievous harm, it is Lawful for him to use such force on the assailant as is necessary for the defence even though such force may cause death or grievous harm.
The defence of self defence by nature is determined essentially on facts and circumstances of each case. See OMOREGIE vs. THE STATE (2008) 12 S.C. (Pt.111) 80. The guiding principles of self defence are necessity and proportion. The two questions which ought to be posed and therefore answered before the trial Court were:
(1) On the evidence, was the defence of self defence necessary?
(2) Was the injury inflicted proportionate to the threat offered? Or was it excessive?
If however the threat offered is disproportionate with the force used in repelling it, and the necessity of the occasion did not demand such a self defence, then the defence cannot avail the Accused. See R. v. Onyea Maizu(1985) NRLR 93.
It is also trite that the defence is weakest where the position of the victim is weaker than that of the Accused, and hence the issues not arise; the defence will also not be available. See; Udofia vs. The State (1984) 9. S.C (Reprint) 51., Adeyeye vs. The State (2013) 1-2 S.C. (Pt.1) 143; Ojo Adeyeye vs. The State (2013) 1-2 S.C. (Pt.1) 143.

For a successful plea of self defence, the following conditions must co-exist:
(a) the accused must be free from fault in bringing about the encounter;
(b) there must be present an impending peril to life or of great bodily harm, either real or apparent as to create honest belief of an existing necessity;
(c) there must be no safe or reasonable mode of escape by retreat; and
(d) there must have been a necessity for taking life.
See: Liyal Vs The State (1988) 2 NWLR (Pt.538) 397; Omoregie Vs The State (2008) 18 NWLR (pt. 1119) 464; Kwaghsir vs The State (1995) 3 NWLR (Pt. 386) 651; Nwambe Vs The State (1995) 13 NWLR (pt.384) 385.