A federal judge in Detroit yesterday ruled that "black English" - spoken by millions of black Americans - could become a language barrier to students if school officials do not take the dialect into account and provide special instruction in standard spoken English to those who speak "black English."

Ruling in a suit brought by 11 black children, Judge Charles Joiner gave the Ann Arbor, Mich., school system 30 days to draft a plan to help teachers recognize "black English" and provide specific steps that can be taken to teach standard English to "black English" speakers.

The ruling in the two-year-old case follows three weeks of testimony from nationally prominent linguists and educators. The plaintiffs contended that the 11 black children, all classified as poor achievers in school, were being discriminated against because the Martin Luther King Jr. Elementary School in Ann Arbor did not recognize the language they spoke as a legitimate learning barrier. The children came from an all-black housing project.

The school board maintained that the "black English" the 11 children spoke was not a language barrier, but a slang dialect of standard spoken English. Attorney John Weaver, defending the school board, pointed out that many black children attended the school, but only the 11 plaintiffs spoke "black English."

"I think you have seen history today that is as significant . . . [as] Brown vs. the Brown vs. the Board of Education," said Gabriel Kaimowitz, attorney for the children since the suit was filed in July 1977. Earlier, Kaimowitz had said such a favorite ruling would have far-reaching implications for "Appalachian dialects and hillbilly dialects" as well as "black English."