A new analysis of hundreds of thousands of cases in federal courts has found vast disparities in the prison sentences handed down by judges presiding over similar cases, raising questions about the extent to which federal sentences are influenced by the particular judges rather than by the specific circumstances of the cases.

The trove of data subjects individual district court judges to a level of scrutiny unprecedented in the history of the judiciary.

In the Eastern District of New York, for example, the 28 judges in the study delivered a median sentence of 24 months for drug cases in the past five years. But there were disparities: Judges Jack B. Weinstein and Kiyo A. Matsumoto gave median drug sentences of 12 months, while the median drug sentence for Judge Arthur D. Spatt was 64 months.

The Eastern District ranked 17th among more than 80 districts in drug sentencing disparities.

Until the release of the data on Monday, it was difficult to review a judge’s sentencing history over time, because public court records in criminal cases could not be searched by the names of judges, only by the names of criminal defendants or lawyers.