The Supreme Court agreed to hear a case today that could put zoning laws on the chopping block. The court agreed to decide whether federal fair housing laws allow cities to bar some group homes from single-family neighborhoods. The case from Washington state involves Oxford House, a group home for recovering alcoholics and drug addicts, established in 1990 in an area zoned for single family homes. City officials took Oxford House to court charging that it violated the city zoning code. But Oxford House called this a form of discrimination that federal fair-housing laws prohibit. A lower court has ruled for the group home.