There’s nothing like a good crisis for stimulating calls to revive long-forgotten laws of doubtful utility. When Liz Truss said last weekend that she saw no problem in UK citizens volunteering to help the Ukrainian war effort in Kiev, harrumphings from the great and good were foreseeable (“sending untrained civilians into harm’s way … ”, etc). In support of their case, however, the critics also dusted off a piece of largely-forgotten high Victorian legislation, the Foreign Enlistment Act 1870, and smugly pointed out that anyone who followed Liz’s advice would probably be committing a criminal offence carrying two years in prison.

They were, of course, correct. But the conclusion to be drawn is not so much that Liz Truss was wrong, as that the 1870 Act is itself a clunking anomaly, and that it is high time it went.

There has only ever been one successful prosecution under the Act

As usual, there is history here. The Act effectively dates from 1819. Tory premier Lord Liverpool as a matter of high diplomacy had assured Spain that Britain was neutral over Latin American independence, but then faced large numbers of Britons who were far from disinterested on the issue and wholeheartedly supported the rebel colonists. To guard the government’s position and reassure Spain, he passed the Foreign Enlistment Act 1819, which made it a crime for British subjects to enlist without the Crown’s leave in foreign national or revolutionary forces (“any foreign prince, state, potentate, colony, province or part of any province or people, or of any person or persons exercising or assuming to exercise the powers of government in or over any foreign country ..”), or to build or equip ships for them.

This may have kept the Spanish sweet, but otherwise it had no effect. Britons still flocked to join the Latin American revolutionaries, and no serious efforts were made to punish them. The same happened with the Greek independence struggle before Britain abandoned its neutrality in 1827. Put briefly, though some inconclusive proceedings were taken in the case of ships built for the American Confederacy between 1860 and 1865, no-one was ever prosecuted for unlawful enlistment under the 1819 legislation.

The 1870 Act replaced the 1819 legislation following diplomatic difficulties associated with the American Civil War. It kept the ban on enlisting with foreign states at war with countries at peace with the UK, though it dropped the reference to rebel forces; it also criminalised the fitting out of military expeditions against friendly states.

Its enlistment provisions remained just as ineffective, however. Threats to prosecute volunteers for helping Prussia in the Franco-Prussian War, either side in the Spanish Civil War, the Zionists in 1948 Palestine, or the FNLA in Angola in the 1970s, were neither heeded nor carried out. Indeed there has only ever been one successful prosecution under the Act, namely that of the man who led the 1895 Jameson Raid into the Transvaal; and this was not for unlawful enlistment but for fitting out a military expedition against a then-friendly country (the South African Boer Republic).

Its ignominious history aside, there are today at least four compelling reasons to get rid of the Act.

First, there seems no obvious justification for a law prohibiting British citizens from enlisting in any other than their own armed forces. The UK itself is, after all, happy to recruit abroad. Apart from the obvious example of the Gurkhas from Nepal, anyone from Ireland or the Commonwealth is welcome to join up. If so it seems a little odd to punish our own citizens for doing exactly the same thing in reverse. This is especially so since the prohibition equally applies to dual nationals. To say that (for example) an Israeli citizen technically commits an imprisonable offence by joining the Israeli army merely because he also happens to have UK citizenship is simply bizarre.

Secondly, it creates foolish anomalies. Take a British cyber warfare expert wanting to help Ukraine against Russia in its hour of need. He is entirely free to join a computing contractor in Kharkiv that works for the military, but if he does exactly the same work as a private in the Ukrainian army he faces arrest as soon as he sets foot back here. Again, assume that the worst happens, Russia wins in Ukraine, and that the UK unwillingly recognises the fact. Apparently the 1870 Act immediately ceases to apply, since from then on the Ukrainian forces would be rebel forces and hence not a state at war with another friendly state. Distinctions like this don’t leave one confident that the Act does any serious good.

British citizens should be free to support what causes they wish

Thirdly, keeping ineffective criminal legislation on the books creates its own problems. This is so both on principle – in a free country criminal laws should be either either enforced or abrogated – and in practice. A government looks ineffective if it nominally prohibits its citizens from enlisting abroad but never bothers to enforces the ban; if it issues empty threats to prosecute but cannot carry them through it looks foolish. Neither is attractive.

Fourth, the problems at which the 1870 Act is aimed – preventing UK citizens dragging it into conflicts it would rather distance itself from – can perfectly well be dealt with in other ways. The supply of ships and weapons of war is now amply covered by export control legislation. Participation in, and training for, terrorism abroad is already a serious offence, and the government has powers under the Counter-terrorism and Border Security Act to prevent citizens from travelling to terrorist hotspots.

The 1870 Act, in short, has now become an unnecessary piece of meddlesome legislation aimed at little more than saving the UK government from embarrassment and giving it the occasional change to virtue-signal by ordering its citizens not to upset the apple-cart abroad. Nearly fifty years ago, indeed, an inquiry set up by the UK government itself under Lord Diplock after the Angola affair came to exactly the same conclusion.

It said that if the government wanted powers to prevent its citizens fighting in particular conflicts, it would be perfectly possible to provide for a limited power to designate such conflicts, but that apart from that the 1870 Act should go. It was right. Today British citizens should (provided they avoid terrorism) be free to support what causes they wish, wherever they wish, and in whatever form they wish. The state has no business stopping them doing so.