The British Foreign Enlistment Act, notification of which had been given in May, 1861, forbade subjects to "be concerned in the equipping, furnishing, fitting out, or arming, of any ship or vessel, with intent or in order that such ship or vessel shall be employed in the service ..." of a belligerent, and provided for punishment of individuals and forfeiture of vessels if this prohibition were disobeyed.

But the Act also declared that such punishment, or seizure, would follow on due proof of the offence.

Here was the weak point of the Act, for in effect if secrecy were maintained by offenders the proof was available only after the offence had been committed and one of the belligerents injured by the violation of the law.

Over twenty years earlier the American Government, seeking to prevent its subjects from committing unneutral acts in connection with the Canadian rebellion of 1837, had realized the weakness of its neutrality laws as they then stood, and by a new law of March 10, 1838, hastily passed and therefore limited to two years' duration, in the expectation of a more perfect law, but intended as a clearer exposition of neutral duty, had given federal officials power to act and seize _on suspicion_, leaving the proof of guilt or innocence to be determined later.

But the British interpretation of her own neutrality laws was that proof was required in advance of seizure--an interpretation wholly in line with the basic principle that a man was innocent until proved guilty, but fatal to that preservation of strict neutrality which Great Britain had so promptly asserted at the beginning of the Civil War[966].
The South wholly lacking a navy or the means to create one, early conceived the idea of using neutral ports for the construction of war vessels.