WASHINGTON, D.C.: California and Arizona voters may have decided that illegal substances can be prescribed in some cases for medical purposes, but federal drug-fighting agencies are not so sure. Little more than a month after the two states passed propositions allowing doctors to prescribe marijuana and other drugs for certain patients, federal officials have announced that they may penalize physicians who choose to exercise this new freedom. Under federal law, it is illegal for a doctor to prescribe Schedule I substances, which include drugs like marijuana and heroin. Federal officials indicated Monday that a plan outlining their response to the new state legislation directs government agencies to continue to enforce this law to the letter. Doctors who abuse their prescription privilege by following the new state rules could lose the right to prescribe drugs, said Drug Enforcement Administration spokeswoman Catherine Shaw. This could prove devastating for physicians, as they need DEA certification to prescribe legal pharmaceuticals. The federal strategy was drawn up by several agencies at the request of President Clinton. The President has yet to review the plan but it has been approved by the DEA, FBI, and the departments of Justice, Transportation and Health and Human Services.