Governor Charlie Baker on Wednesday signed into law a bill that will once again allow Massachusetts schools to teach English language learners in their native tongues. It overturns an ill-conceived experiment highlighting the perils of government by referendum.

The move reverses a ballot question from 2002 that required English learners to be taught in so-called "sheltered immersion programs" whereby, with few exceptions, books and lessons were in English rather than students' native languages.

The educational constraints imposed through the sheltered immersion program contained more than a whiff of xenophobia. The ballot went before voters following 9/11, spearheaded by millionaire software developer Ron Unz, who stressed the benefits of children learning English as quickly as possible without taking into account that not all English language learners are the same. Mr. Unz, who led two successful referendum campaigns in Arizona and his native California, found an ally in then-gubernatorial candidate Mitt Romney, who made ending bilingual education one of the planks of his campaign at a time when anti-immigrant sentiment was gaining political traction.

The initiative was opposed by educators who understood its ramifications. Indeed, the sheltered-immersion-only requirement has failed to close the achievement gap between native English speakers and their non-native peers. This is no small matter in Massachusetts, where the number of English learners in our public schools has doubled to more than 90,204 students — or 9.5 percent of the student population — since 2000, according to House Speaker Robert DeLeo's office.

Most English language learners are in the early elementary grades at an age in which language acquisition proves easier. By comparison, data show that high school English language learners have a far more difficult time, which has led to a four-year dropout rate that exceeds 14 percent, almost three times higher than the state average. Between 50 and 84 percent of English language learners scored "warning/failing" on last year's MCAS test, depending on the subject.

What the ballot backers assumed wrongly was that the vast majority of English language learners would quickly and comprehensively learn their adopted language. This simply hasn't been the case. Moreover, nearly a decade into the ballot law, a federal investigation found that at least 45,000 teachers in 275 districts throughout the commonwealth were inadequately trained to teach sheltered immersion. Those who were know that students vary in learning capacity and teachers must have flexibility.

Under the new law — which passed the Senate unanimously and the House on a 155-1 vote — school districts are given the latitude to choose the program that best serves its students, including immersion in specific cases. Governor Baker said the new law "preserves an existing approach that works well for many students, while providing school districts with the opportunity to adopt alternative, credible ways to teach English that may be more beneficial for certain students."

The new law contains another positive element to it. It charges the Department of Elementary and Secondary Education with developing "seals of biliteracy" for high school diplomas to recognize students who are proficient in English and another language. For English learners, no more will their native tongue be treated as a liability. Rather, it will be treated for what it is: a highly valued asset in this global economy.