In years of dominance of natural law and philosophy of laissez-faire the carrier was able to protect his interests by broadly drafted clauses, with very wide range of options regarding to places where it was lawful for ship to call to. The cargo interests, on the other hand, were resolute in restricting the meaning of such provisions within the following limits:
a) description of voyage
b) justification of departure from the direct route
c) the justice of the case .
The Teutonia (1872) LR 4 PC 171, 1 Asp MLC 214, at page 179:
It seems obvious that, if a master receives credible information that, if he continues in the direct course of his voyage, his ship will be exposed to some imminent peril, as, for instance, that there are pirates in his course, or ice-bergs, or other dangers of navigation, he must be justified in pausing and deviating from the direct course, and taking any step which a prudent man would take for the purpose of avoiding the danger.
Stag Line Ltd v Foscolo Mango & Co Ltd  AC 328, HL, per Lord Atkin:
For the purpose of uniformity it is therefore important that the Courts should apply themselves to the consideration only of the words used without any predilection for the former law…
Having regard to the method of construction suggested above, I cannot think that it is correct to conclude as Lord Justice Scrutton does that Rule 4 was not intended to extend the permissible limits of deviation as stated in the Teutonia, L.R. 4 P.C. at p. 179. This would have the effect of confining reasonable deviation to deviation to avoid some imminent peril. … A deviation may, and often will, be caused by fortuitous circumstances never contemplated by the original parties to the contract and may be reasonable though it is made solely in the interests of the ship or solely in the interest of the cargo or indeed in the direct interest of neither; …
The true test seems to be, what departure from the contract voyage might a prudent person controlling the voyage at the time make and maintain, having in mind all the relevant circumstances existing at the time, including the terms of the contract and the interests of all parties concerned, but without obligation to consider the interests of any one as conclusive?