A lawyer for Jose Padilla, a US citizen accused of plotting to detonate a radioactive “dirty bomb,'’ went before a federal appeals court Tuesday and demanded the U.S. government either charge his client with a crime or set him free. But a Bush administration lawyer told the court that the president must have authority to indefinitely detain terror suspects. President Bush declared Padilla an “enemy combatant,'’ a designation that allows the military to hold someone indefinitely without charges. Padilla is in the Navy brig in Charleston, S.C., and has been held for the past three years. The appeals court received the case after a South Carolina judge ruled that the government must charge Padilla with a crime or release him.