At the heart of the government’s immigration policy is a single target: to bring annual net migration below 100,000 by the next election. There are multiple problems with this; problems of fact, problems of interpretation and damaging consequences arising from its callous implementation.

Net migration is the difference between immigration and emigration, calculated by subtracting the number of people leaving the UK for a year or more from the number arriving for a year or more. It includes British, EU and non-EU citizens moving in both directions. For the year ending June 2013, there was immigration of around 503,000 and emigration of 320,000 causing net migration of 182,000. Net migration for 2010, the year the coalition took power, was 252,000.

The first problem with the net migration target is that the number of people entering and leaving Britain is not actually counted. The figures used are primarily based on a sample of around 5,000 migrants identified through the International Passenger Survey, which surveys people travelling through UK air and sea ports. The margin for error means that we can be 95% confident in the net migration figure plus or minus roughly 35,000. A recent parliamentary report on Migration Statistics judged them not fit for purpose, stating, “The Government should not base its target level of net migration on such an uncertain statistic: doing so could lead to inappropriate immigration policy.”

The second problem stems from focussing solely on net migration when it is only one part of a complex picture. For example, this year the government was criticised when net migration rose by 15,000, even though immigration fell by 14,000. Net migration rose because fewer people emigrated than the previous year. In fact most of the rise could be accounted for by the fact that 12,000 fewer British people emigrated than the previous year. Absurdly the government ‘failed’ mainly because not enough British people left the country.

The third problem is that many factors determining net migration lie beyond the government’s control. British citizens may come and go as they please, so the government can’t affect their numbers. All citizens within the European Economic Area (EEA) - EU citizens plus nationals from Iceland, Liechtenstein, and Norway - have right of free movement, so the government can’t interfere with their numbers either. This leaves non-EEA citizens to bear the weight of these targets. For the government to achieve their numerical aim, this group of migrants will be disproportionately penalised to compensate for the areas outside the government’s control.

Targeting non-EEA citizens, the government first reduced the number of skilled workers who could enter the country, as the previous government had already stopped the recruitment of low-skilled workers. UCL’s Migrant Research Unit judged the targeting of skilled workers “a surprising choice” which “only made sense as a means of trying to cut overall net migration”. Students from outside the EU were the next to be clamped down upon, resulting in a loss of income to the education sector from international students.

Changes to family rules were exceptionally cruel. Since the 9th July 2012, British citizens who wish to have their non-EEA spouse, fiancé or partner join them in the UK must demonstrate that they have a minimum gross annual income of £18,600. This figure rises significantly for each child. As the Migration Observatory have pointed out, 47% of British citizens in employment wouldn’t meet the threshold. The policy is dividing families and sends the heartbreaking message that only the well-off are permitted to live here with foreign loved-ones. It has also become virtually impossible for British citizens to bring a non-EEA elderly dependent relative to live with them. Families are forced to choose between living apart or abroad. Yet this private tragedy is a double-win for government statistics; rather than one family member coming in, they could score a whole family going out.

The Liberal Democrat MP Sarah Teather, who decided not to stand for parliament at the next election partly in response to these immigration policies, articulated the crux of the issue, “The problem is that the impact on individual lives gets lost in the grandstanding of headlines. When immigration is all about reducing numbers on a spreadsheet to meet an arbitrary cap ... the subjects of the legislation – the human beings at the centre of it – are somehow invisible.”

Net migration is an unreliable measure, an incomplete indicator and is largely beyond the government’s control. Using it as a sole policy driver is misguided, damaging and inhumane. Sadly, rather than shine a light on the government’s poor decision-making, Labour’s response is to crow over any failure to hit the target. This cheap point-scoring politics serves nobody, ruins lives and demeans us all.