Blacks, Latinos, and Asians together make up more than 40 percent of the state's population.
"The court should reflect the diversity of the citizenry of the state," said Assembly Speaker Sheila Oliver (D., Essex), an African American and member of the legislative group that sent the letter. "I know the governor is very proud of the gender representation on the court. We also have to have racial and ethnic diversity."
Assemblywoman Bonnie Watson Coleman (D., Mercer), also an African American and a member of the group, said that New Jersey courts have long been respected around the country for diversity, fairness, and independence, and that Christie has put that reputation at risk by allowing the Supreme Court to convene without any minority representation.
"Nominees must be a reflection of our population," she said.
Christie did not reappoint the court's last African American justice and nominated a white woman to fill a vacancy when the court's only Hispanic member resigned.
Christie said in May that he would be mindful of minority concerns when making his next appointments.
"We have an obligation to put the very best people on the court and to have a court that represents all of the interests of the people of New Jersey," Christie said at the time. "Certainly that's something I'll be mindful of as I consider nominees for those two seats."
His spokesman, Michael Drewniak, said Thursday he had nothing to add.
The high court had been integrated since 1994, when the first African American justice, James Coleman Jr., took his seat, said Winnie Comfort, a spokeswoman for the state's judicial branch. Coleman was followed by John Wallace in 2003. Wallace was not reappointed by Christie.
The only Hispanic justice, Roberto Rivera-Soto, finished a seven-year term in September and declined to seek reappointment.
The struggle over the composition of the court began about 18 months ago when Christie became the first governor in memory not to reappoint a sitting justice for tenure.
His action - which he said he took to reshape a bench he viewed as too activist - left the highest court without an African American representative for the first time in 16 years.
Democrats refused to consider Christie's nominee, corporate lawyer Anne Patterson, for more than a year. Senate President Stephen Sweeney (D., Gloucester) and Christie eventually brokered a deal to move Patterson's nomination - as a successor to Rivera-Soto, who had decided not to seek tenure on the court.
Meanwhile, Democrats vowed to keep Wallace's seat vacant until March, when the jurist would have reached the mandatory retirement age of 70.
Justice Virginia Long also will turn 70 in March.
Jerome Harris, who heads the state's Black Issues Convention, said the issue of judicial diversity was being closely watched, especially because big court issues such as affordable housing, public school funding, and racial profiling can have dramatic effects on minority communities.
"Maintaining diversity on the court contributes to its independence," he said, noting the available pool of qualified minority lawyers seeking judgeships. "Under no circumstances are we suggesting that the quality of the appointments be diminished to achieve diversity."