Thanks to the Innocence Project and the overturning of 18 wrongful convictions of death-row inmates with DNA evidence and the exonerations of 16 others charged with capital crimes, the American public is increasingly aware that the system makes terrible mistakes. Since 1973, a total of 142 people have been freed from death row after being exonerated with DNA or other kinds of evidence.

All of these factors have led the states to retreat from the death penalty in recent years — in both law and in practice. In 2012, Connecticut became the fifth state in five years to abolish the penalty. Nine states executed inmates, the fewest in two decades. Three-fourths of the 43 executions in 2012 were carried out in only four states. The number of new death sentences remained low at 77 — about one-third the number in 2000 — with just four states accounting for almost two-thirds of those sentences. While 33 states retain the death penalty on their books, 13 of them have not executed anyone for at least five years.

Those 13 states plus the 17 without the penalty means that 30 states are not carrying it out — and that includes California, which retained the death penalty in a November referendum vote. Almost one-quarter of the 3,146 death row inmates in the United States, as of October, are imprisoned in California, but that state has not executed anyone in seven years.

California’s chief justice said recently that the state’s official moratorium, which has been in place for six years, is likely to continue for at least three more because of problems with the execution method.

In January, executions are scheduled to take place in Pennsylvania, Virginia and Texas. As it happens, major reviews of the death penalty are under way in each of those states. The reviews are very likely to find that those states have failed to meet standards of fairness under the Constitution, just as reviews of the capital systems in other states have concluded in the last decade.