A judge ruled Amy Locane was able to understand the consequences of waiving her rights even though she was "clearly intoxicated" and sedated with anti-anxiety medications.
A police officer testified the actress was giggling and laughing after a motor vehicle crash that claimed a woman's life in Montgomery in 2010.
Prosecutors allege the 39-year-old, who lives in Hopewell, was drunk and speeding when her SUV struck a vehicle that was pulling into a driveway.
The Star-Ledger of Newark reports her lawyer declined to comment on the judge's ruling.
The trial has not been scheduled.