Donald Trump uses nativist anger to put his government beyond empirical argument. His presidency has eroded the norms of political conflict. He poses an ever-present danger to democracy. This November, Mr Trump is up for re-election. His effort is built to an alarming degree on exploiting the United States’s lack of privacy safeguards around voting intention.

Digital campaigning in the US is a largely unregulated field with little oversight of the ways in which voters are targeted or manipulated. Politicians in the US want to target specific voters to increase their base’s turnout, convert the undecided and suppress their opponent’s support. The evidence suggests that Trump’s campaign rests on a data-gathering juggernaut that wants “to know who [voters] are and how [they] think”.

Mr Trump’s team and other allied conservative groups are focusing on voters’ smartphones and their location histories. Phone apps often broadcast their location to data brokers and advertising firms. It does not take much to work out where the phone’s owner lives and works. The data can show where they going jogging or if they go to church, or if they attended an anti-Trump protest on a given day. While apps’ privacy policies might say that location information is used for advertising, the use of such data for invasive political purposes is rarely disclosed. Apps do not make it easy to tell how they collect information and with whom they share it.

As a result, techniques such as “geofencing”, which allows campaigns to reach people in a particular area, are becoming widespread. Last year, Brian Burch, the president of CatholicVote.org, a conservative group, claimed its work in Wisconsin identified 91,373 mass-attending Catholics who were “not even registered to vote”. This in a state where Mr Trump defeated Hilary Clinton by only 22,748 votes. Democrats do it too, but are way behind. Last year, Beto O’Rourke’s team was able to identify people’s mobile ID numbers during a rally with musician Willie Nelson. These were used to match people with email addresses to identify “Beto” supporters.

India’s Narendra Modi is a leading exponent of such campaigning. In 2018, it was revealed that the default permission settings of his NaMo app gave it almost full access to the data stored on users’ phones, including audio, photos and videos, contacts and location services. Cybersecurity researchers said the app was sending user data to a US-based analytics company – allegedly without users’ permission. In the US, data collection from apps is legal as long as it is disclosed. The European Union forbids the collection of sensitive data – like that of religion, health or political opinions – without explicit consent. The concern is that although EU law has been imported into UK statute, it may be unwound in the years ahead. This would open the door to the kind of deceptive practices seen in the US that have undermined user privacy and have given rise to new legal and ethical concerns in this year’s presidential campaign.