He added that while other states have expressed interest in the plan, none has ever passed a similar law.

The state of Illinois began using such a program at its public colleges last year, and other states have expressed interest.

Other states have expressed confidence in the efficacy of the system.

Even before the second world war the United States expressed an interest in it.

Nine other states have expressed strong interest, according to New York officials.

Boeing put out a call for proposals last month, nearly a dozen states quickly expressed interest.

Some states, though, have expressed doubts about the laws' effectiveness.

Finkel said six states and two countries had expressed interest, but he would not identify them.

The United States and international human rights groups expressed concern over the killings.

The United States has expressed the hope that this could be achieved within 6 to 12 months.