The threat of bioterrorism has led to a reinvestment in public health, but not necessarily in a manner that ensures efficient, reliable and cost-effective improvement in services. Public health officials fear that homeland security is distorting the priorities of public health and diverting resources from the essential work they are already doing. They fear that homeland security requirements may have erosive effects on confidentiality and in compromising their core mission of health promotion and disease prevention. Specific issues include cutbacks in promised support, diversion of funding to single-purpose projects, concerns over maintaining confidentiality of client services, abuse of the extensive police powers given by state legislation to public health authorities, and lack of integration with existing public health systems. The reasons for these concerns are deeply rooted in the history of public health, in which the legal authority of health agencies included police powers and even detention. Public health leaders would prefer a policy of “dual use” or “dual benefit” in which capacity is added to enhance the operation of the public health system in general while adding new capability in emergency response. Such a policy would ensure benefit from the investment even if no bioterrorism event ever occurred locally and would enhance the reliability of the system. For example, a single-purpose surveillance program for bioterrorism is likely to have an unacceptably a high risk of failure and unreliability in a bioterrorism event if it is not regularly tested by the type of outbreak that occurs many times a week in every metropolitan health department. A small but articulate group of public health leaders, led by Victor W. Sidel, have even questioned the ethics of collaboration between public health and police or intelligence services. This article suggests that such cooperation is actually necessary and recommends advance guidelines and policies, legal clarification, combined multidisciplinary training, and mutual trust and understanding among public health, law enforcement, and intelligence professionals, in order to protect the integrity of essential services and the valid concerns of the public health system.