WASHINGTON. — Washington -- Minnesota's Supreme Court has unleashed an idea that may be a harbinger of much future mischief. The idea is that a criminal statute that has a disparate impact on a minority group may be unconstitutional, even if the legislature that wrote it had no discriminatory intent or purpose. This idea may be the first swelling of the next wave of judicial activism as liberals turn from federal to state courts.
In Minnesota, persons possessing three or more grams of crack cocaine or 10 or more grams of cocaine powder are guilty of a third-degree offense. Last December a district judge in Minneapolis dismissed charges against five black men because the law imposes heavier sentences for the possession of crack than for the possession of the same amount of cocaine powder. Crack is used primarily by blacks, powder primarily by whites. Therefore, the judge said, the law violates the Minnesota Constitution's guarantee of equal protection of the law.
Now the state Supreme Court, in a ruling that may affect upward of 100 pending cases, has sided, 6-1, with the district judge. Distilled to its essence, the court's ruling is that the results of the law are bad policy, produced because the legislature did not reason about the drug problem as the judges wish it had reasoned.
The court upheld the district judge's opinion that there was ''no rational basis'' for the legislature's distinction between crack and powdered cocaine. The court, free-lancing as a certifier of what constitutes appropriate data, disdained the legislature's reasoning as based merely on ''anecdotal'' evidence concerning the more dangerous nature of crack.
''Anecdotal'' implies random bits of data. ''Empirical'' would have been a less tendentious description of the testimony of experienced law-enforcement officers, or of a lawyer who handled 700 narcotics cases in four years.
Because crack is smoked, it reaches the brain faster than cocaine that is sniffed. Many scientists suspect that it produces more rapid addiction. But the court, determined to reach the result it prefers, said that if powdered cocaine is dissolved in water and injected intravenously (which it rarely is, but never mind), the physiological effect is similar to the effect of smoking cocaine. The relevance of that fact to the legal issue is, to say no more, obscure.
Because the high from smoked crack does not last as long as the high from sniffed cocaine, the need for more frequent doses makes crack users especially prone to violence. However, in a crashing non sequitur the court says violence associated with crack use may reflect sociological (gang culture, for example) rather than pharmacological factors, therefore -- therefore? -- more severe punishment of crack possession is unjustified.
The court's lone dissenter, Justice M. Jeanne Coyne, made mincemeat of the majority's ruling. The court, she said, simply supplanted the legislature's view of the basis for, and efficacy of, statute with its own view. Courts have no right to usurp from legislatures -- representative institutions constituted to respond to the will and values of the people -- the responsibility for determining appropriate punishment for particular crimes.
A statute that is facially neutral and serves legitimate governmental ends does not violate the equal-protection guarantee unless the legislature is proved to have had a discriminatory intent or purpose. A disparate impact of a law on a particular social group does not prove invidious discrimination. (Anyway, what is the word ''discrimination'' doing here? Do laws against speeding ''discriminate'' against teen-age boys?)
Ms. Coyne correctly applies the U.S. Supreme Court's rule regarding the U.S. Constitution's equal-protection clause. But Minnesota's court relied on the state consti- tution's clause.
We may see more such rulings. Liberals, relying on judicial activism (rather than domestic persuasion), may retreat from federal courts, where almost two-thirds of the judges are Reagan-Bush appointees. They will turn to state courts, inciting more liberal judges to use state constitutional language as pretexts for judicial legislating.
Minnesota's Supreme Court disapproved of the provision equating 10 grams of cocaine powder and three grams of crack. But the Federal Anti-Drug Abuse Act of 1986 equates 100 grams of powder with one gram of crack. The Minnesota judges who will not tolerate the 10-to-3 ratio do not care that all challenges to the 100-to-1 ratio have been rejected in federal courts.
Most Minnesota crack arrests result from raids on crack houses, which are disproportionately located in black neighborhoods. According to the Minnesota Office of Drug Policy, the reason for the large number of raids on such houses is that ''neighbors clamor for them.''
The legislature did not anticipate a disparate impact of the sort the statute produced. (In 1988, 96.6 percent of Minnesotans charged with possession of crack were black; 79.6 percent charged with possession of powder were white.) Arguably, the law should be changed because it creates a problem of perception in the black community. But only result-oriented sophists argue that judges should short-circuit representative government to impose policies they prefer.
George F. Will is a syndicated columnist.