What is the effect of an instruction to a jury in a personal injury action where defendant assumed that plaintiff's employer had provided plaintiff with a safe place to work?

The effect of the instruction was to inform the jury, categorically, that it was reasonable for defendant to assume that plaintiff's employer had provided plaintiff with a safe place to work, without qualification as to any knowledge defendant himself might have and regardless of the fact that defendant might be shooting squarely at a place in which he knew plaintiff to be. It completely removed from the jury the question of the reasonableness of the assumption that an independent obligation between plaintiff and his employer would not be violated, despite the fact that defendant himself was operating a dangerous instrumentality, fraught with peril toward plaintiff unless extreme caution were employed. The general principle relied on by defendant in support of the instruction that one has a right to assume that another will obey the law was not only inapplicable in the context here present, but contains a significant qualification. 'It is only when there is nothing in the situation to warn him of impending danger that he is not guilty of negligence in relying upon such assumption. The reasonableness of the conduct of a person relying upon the assumption that another will obey the law is primarily a question for determination by the trier of fact [citations].' Shiya v. Reviea, 122 Cal.App.2d 155, 163, 264 P.2d 190, 196. Under the instruction, the court told the jury that as a matter of fact defendant 'was entitled to assume that plaintiff's employer had furnished to plaintiff a safe place within which to work.' For the various reasons stated, the instruction should not have been given.