Lawyers for a parent group and the Boston School Committee differed Tuesday on the motivations behind temporary changes in admissions to the city's exam schools. A representative of white and Asian parents argued the plan was racially motivated, while the committee's counsel cited the pandemic and several diversity goals.

The arguments came in a federal lawsuit filed by Boston Parent Coalition for Academic Excellence that contends the admissions plan for this year discriminates against white and Asian applicants in some neighborhoods. Because COVID-19 prevented the administering of an admissions test, the school committee last fall adopted a plan for this year to use grades received before the pandemic and zip codes to select students for Boston Latin School, Boston Latin Academy and the John D. O'Bryant School of Mathematics and Science.

The issue before U.S. District Judge William G. Young is whether race played such a big role in shaping the plan he must apply the highest level of judicial scrutiny or defer to the committee because its approach has a sound rational purpose. Young, whose courtroom is in Boston, presided over the virtual trial and indicated he hopes to issue an order by April 15 so the school department can send out invitations to attend the exam schools. He could issue an injunction or decision or request more evidence.

"The zip code quota plan is racially motivated," declared William Hurd, representing the parents. "It doesn't matter which race or races were targeted."

When Young challenged Hurd, calling the use of zip codes "race neutral," he replied that racial balancing was the "predominant reason, perhaps the only reason" for adopting the admissions process. Hurd called the use of zip codes "a sham" to achieve desired racial results.

Simulations done for an internal working group that drafted the plan projected the numbers of white and Asian students admitted would decrease, while the count of Black and Latino applicants would rise. The enrollment of Boston Latin is overwhelmingly white and Asian, almost the reverse of their presence in the school system. The racial-ethnic composition of Latin Academy and the O'Bryant School are less skewed.

"The plan is race neutral," said Kay Hodge, the committee's lawyer. "Calling that plan a zip code quota plan doesn't make it so."

Hodge conceded racial equity was a concern but the "overarching issue" in crafting the admissions process was adjusting to COVID-19 and creating opportunities for homeless students and ones from low-income families. "The interim plan is about socioeconomic and geographic diversity," she said.

Under the plan, 20% of seats in the schools would be filed based on GPAs. The remaining 80% are to be decided based on zip codes, with the ones with the lowest family income going first in multiple rounds. Seats will be allocated to each zip code based on the number of school age children there. Homeless students and ones under state supervision will be group together and get the very first choice in the rounds to fill most of the seats.

Hurd disputed that socioeconomic diversity was a major motivation.

"Why have they been so harsh on Chinatown?" he asked, citing the low income level in the neighborhood. "It is one of the zip codes losing the most seats."

Hodge disputed that Chinatown would face a disproportionate impact. Exam schools admit sixth graders. She said some of the 44 students who live in the neighborhood could be admitted based on GPAs. She also indicated there are 67, 44 and 34 Asian sixth graders in three Dorchester zip codes.

"There may be an Asian students from Dorchester that gets in" who might not otherwise, she said. "There could be far more Asians under the zip code plan."

Hodge suggested the lawsuit was filed because "some children in Chinatown, some children in West Roxbury, (think) they have a lock, they own those seats."

Young allowed the Boston NAACP and other groups to intervene on the school committee's side and permitted its lawyer to join the arguments.

Doreen Rachal, a lawyer for the intervenors, suggested the plan could have a minimal impact on Asian applicants because they are projected to receive 16% of the invitations to exam schools, compared with 17% if only GPAs are used.

"There are no seats guaranteed to any particular student in the city," Rachal said.