It sounds to me like your father was removed for committing an aggravated felony (trafficking). After 1997, when you are deported for an agfel you are permanently inadmissible. However, it would be worth the price of a consultation with a specialist to have a thorough review of your dads case. I'm sorry!
You need to have an experienced immigration attorney review the record of conviction as well as any other conviction records that your father may have.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.