This blog is not noted for sympathy for politicians, but it is hard not to feel sorry for legislators tasked with reconciling the irreconcilable on immigration: they must not only strike a very delicate balance on policy but must then cement that delicate balance in a general law that, by the very nature of law, must apply fairly inflexibly in all cases.

Western statesmen are terrified, with good reason, by the prospect of a flood of economic refugees from failed or failing states, prompting their own voters to complain, rightly or wrongly, about immigrants “stealing our jobs”.

At the same time, all but the very dimmest – who are usually to be found on the extremes of the political left and right – accept that it is in their national interest for their respective countries to attract entrepreneurs from abroad. These people, far from “stealing jobs”, generate employment and wealth for themselves and those among whom they live.

However, in practice, it is very difficult to identify such desirable immigrants and separate them from the less desirable.

For example, the United States has long had a policy of granting visas to those with money to invest who buy an exisiting business, but this is a blunt instrument. One of its major failing is that it discriminates not on talent or initiate but whether your home country offers a reciprocal arrangement. This is not good business.

Its lack of success has led to many demands for reform. The latest, from Senators Kerry and Lugar, is an initiative those starting up new ventures, as opposed to buying existing operations, can get a visa. Instead of restricting eligibility to country of origin it will be controlled by cash raised from VCs.

Broadly, this is the sort of pro-entrepreneurial initiative we favour, especially as it encourages people keen on making many as opposed to those who already have it. However, this new system, though an improvement, is not without its faults.

It is not that difficult to put a lump of cash in a bank account and claim to be an entrepreneur. Indeed, the easiest way to do it is to obtain the money illegally, or at least dishonestly.

A genuine entrepreneur may not, in fact, have much cash in hand: his real asset is his initiative. It is his desire to make money that drives him to build his business – and adds wealth to the economy in which he operates.

So perhaps the best immigration policy is not a wealth test but an initiative test.

Entrepreneurs have always been mobile, even before modern transport and the global economy. Merchants pioneered trade routes long before the explorers and armies sent by kings. Being one step ahead of the state is part of our job description. Where there is a market, we will find a way in. One way or another, we will find a way around regulations intended to keep us out. So the tougher the immigration law, the greater the challenge – and the higher the calibre of the entrepreneurs who will overcome it.