The paper suggests that when capital punishment was an option, juries were often reluctant to convict at all.
They may have felt it was a little rum to send someone to the gallows for stealing a cow, so they downgraded the charge or acquitted the defendant.
The authors find that juries were particularly reluctant to convict women.
Once death was off the table, however, jurors could convict with a clearer conscience.
The paper finds that the abolition of capital punishment increased the chance of conviction for all crimes by around eight percentage points, with especially large effects for violent offences.
The temporary halt of penal transportation during the American war of independence had a somewhat smaller effect on the likelihood to convict, suggesting that juries considered living in America to be a prospect slightly less awful than death.
Past research has found that would-be criminals are more put off by an increased likelihood of conviction than they are by more severe sentences.
If so, then getting rid of the most brutal punishments could make criminal-justice systems work better.
If the third of Britons who would like the death penalty reintroduced got their way, the country might inadvertently end up letting more criminals walk free.