Britons vote today if they want to remain in the European Union or leave.

The referendum on a so-called Brexit has been increasingly contentious and emotional. Among the most deeply felt issues has been immigration. 

Those favoring a Brexit say that immigrants willing to work for low pay have taken jobs from British workers, driven down wages and stressed public services. But they have relied on misleading information to make their case.

Leave campaigners say there has been a net migration increase. Net migration' is the number of people immigrating to the UK minus those emigrating from it. According to the Office of National Statistics, the long-term net migration rose to 333,000 in December 2015, a 3% increase from September 2015, while net migration of EU citizens increased 5.7% from 2014 to 2015. 

Speaking on BBC Breakfast on Wednesday, the leading Brexit campaigner, Boris Johnson spoke of taking "back control of our immigration system," and taking "back control -- fundamentally -- of our democracy."

Yet policies that allow for free movement across borders tend to help economies by boosting innovation and productivity. Studies have repeatedly shown that current immigrants help more through taxes than they cost in public services. According to the Financial Times, "EU migration does not cut people's pay, even for the low paid."

The Guardian wrote recently that, "a better world means working across borders, not sheltering behind them."

Those opposing a Brexit say that that their opponents are sowing fear. In a BBC Debate on Tuesday, London Mayer Sadiq Khan, a prominent Brexit opponent, called the Brexit campaign hateful.

The Brexit vote could affect three million EU immigrants, many non EU workers and Britons working in other EU countries.

A number of polls over the past few days have indicated that supporters of remaining in the EU are likely to prevail, although the vote is expected to be close. In a Financial Times poll of leading polls Wednesday, 47% of respondents said that they wanted to stay in the EU compared to 45% who said that they preferred leaving. In the The Economist magazine's poll tracker 44% of respondents favored remaining while 43% wanted to leave. 

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.