51.   But cellular industry expert Herschel Shosteck noted that with current technology, it would cost the industry several billion dollars to install such a system nationwide.

52.   But African-Americans and Latinos are heavily in favor of such a system.

53.   But designing and building such a system has proven difficult.

54.   But Everett Brenner, an expert in information retrieval systems, is not convinced that such a system is the best answer.

55.   But he added that in his view such a system will not cause a court to rule in their favor.

56.   But he also said that the London and Frankfurt markets would decide in the next six months how such a system would work.

57.   But he appeared to be reflecting an undercurrent of concern that if the United States put such a system into effect, Europe would be left more vulnerable.

58.   But federal prosecutors said there was no evidence that such a system ever existed.

59.   But in response to inquiries about carry-on baggage checks, he said financial and logistical constraints would make such a system difficult.

60.   But in a crowded country like Japan, such a system could be a solution to the space problems in tall buildings.