In the past 20 years, whites have become less likely to perceive bias, the poll indicated. In 1993, 33 percent of whites surveyed in a similar poll said the justice system is biased against blacks -- 8 percentage points higher than the most recent study.
The poll of 2,541 Americans was conducted after George Zimmerman's not guilty verdict in the killing of 17-year-old Trayvon Martin was handed down, Gallup said.
Overall, 43 percent of those surveyed said the verdict was right, while 40 percent said it was wrong.
Eighty-five percent of blacks said the verdict in the case was wrong while 54 percent of whites said the verdict was right.
Gallup said the results are almost exactly the opposite from O.J. Simpson's innocent verdict in 1995 when 89 percent of blacks said the jury was right while 53 percent of whites said the decision was wrong.
The poll was conducted July 16-21. The sampling error is 2 percentage points, Gallup said.