Abstract When scientists and lawyers meet in the litigation arena their backgrounds and perspectives set them apart. Each has different expectations of the process and criteria by which the court searches for truth. In the Love Canal trial, the worlds of the scientist and lawyer came together as data and expert opinions from soil scientists, hydrol-ogists, engineers, and geologists were integrated to develop an understanding of the migration of contaminants away from the site. Issues related to the age and genesis of the fractured clay that forms the walls of the Love Canal landfill were important to the State of New York in proving that the chemical company, which disposed of the chemicals in the canal, was liable for the migration of dense nonaqueous phase liquids (DNAPLs) through the fractures to the surrounding properties. In particular, it was important to know whether the fractures were formed only as the result of recent excavations for sewers and homes in the 1960s and 1970s, or whether the fractures were present at the site when the chemical company was disposing of chemical wastes in the canal in the 1940s and 1950s. It was concluded that these fractures have been present for at least hundreds of years, and probably were formed during the mid-Holocene. The level of confidence in these conclusions differed between the scientist and lawyer, and those differences had to be reconciled through trial preparation.