The study found that the likelihood of a case containing one or more motions for summary judgment increased before the three 1986 U.S. Supreme Court cases of “Celotex,” “Anderson,” and “Matsushita,” which have been widely viewed as a turning point for the use of summary judgment. These cases signaled a greater emphasis on summary judgment as a necessary means for responding to claims and defenses that lack sufficient factual support. The current study found however, that before these cases were decided, summary judgment in the six Federal courts examined increased from approximately 12 percent in 1975 to 17 percent in 1986, and has remained fairly steady at approximately 19 percent since that time. This increase in summary judgment reflects, at least in part, an increase in filings of civil rights cases, which have typically had a high rate of summary-judgment motions. Unexpectedly, no statistically significant changes over time were found in the outcome of defendants’ or plaintiffs’ summary-judgment motions after controlling for differences across courts and types of cases. These findings do not support the popular view that the aforementioned trilogy of Supreme Court cases led to expansive increases in summary judgment, which some commentators believe has expanded to the point of threatening the right to trial. The current analysis suggests, instead, that changes in Federal civil rules and case-management practices before these three cases in 1986 may have been more important in the change found in summary-judgment practice. 4 tables, 8 figures, and 62 notes