Across the United States and Europe, software is making probation decisions and predicting whether teens will commit crime. Opponents want more human oversight.

“ The technology builds on statistical techniques that have been used for decades, often for determining risk. They have been supercharged thanks to increases in affordable computing power and available data.

The private sector uses such tools all the time, to predict how likely people are to default on a loan, get sick or be in a car wreck, or whether they will click on an internet ad. Governments, which hold vast amounts of data about the public, have been eager to tap their potential...

Across the United States and Europe, software is making probation decisions and predicting whether teens will commit crime. Opponents want more human oversight.

“ The technology builds on statistical techniques that have been used for decades, often for determining risk. They have been supercharged thanks to increases in affordable computing power and available data.

The private sector uses such tools all the time, to predict how likely people are to default on a loan, get sick or be in a car wreck, or whether they will click on an internet ad. Governments, which hold vast amounts of data about the public, have been eager to tap their potential...