The majority of States' anti-spam legislation was superseded by the federal act which took effect earlier this year. However, the Maryland law specifically addresses deceptive e-mailing practices, allowing residents of the state to sue for damages if they receive e-mails containing misleading information.

According to reports in the national media, Judge Thompson took exception to the fact that although the legislation covers Maryland residents, it does not make clear whether it can be applied when they are not physically present in the state.

The vague wording of the legislation, he suggested, could mean that commerce which never enters Maryland could be regulated there. This represents a violation of the commerce clause of the US Constitution, which reserves for the federal government the power to regulate inter-state commerce.

Maryland's attorney general, J. Joseph Curran Jr, however, has reportedly stated that the ruling will have no effect on the enforcement of the law, arguing that:

"The law over the internet is developing. There are going to be conflicting rulings."