Mr. Smith vs. illegal hiring

Attorney General Smith changed his mind. Why not Congress? The topic is penalties for employers who knowingly hire illegal aliens. Mr. Smith originally opposed them. This week he told Congress how he came to realize employer sanctions are an essential enforcement tool for proposed legislation - which passed only the Senate last year - to stem a flow of illegal immigrants he estimates at 500,000 a year otherwise.

What about ethnic discrimination by employers tempted to turn an applicant down on the basis of physical appearance in order to avoid the risk of hiring an illegal? The attorney general says safeguards in the law actually ought to result in reduced discrimination.

What about the threat of imposing a national identity card on all Americans as part of the effort to detect illegals? ''We should do nothing that would result in a national identity card,'' Mr. Smith asserts.

A debate is not ended with an attorney general's words. But if the administration gets behind them the immigration bill might not languish until it runs into the roadblock of another election year, as it did in 1982.