1.   And at a campaign appearance in Manhattan on Sunday, Hillary Rodham Clinton called for increased federal spending on research to improve police technology, including gun detectors.

2.   Once in use, however, the new gun detectors are expected to raise novel constitutional questions about police searches for which there are no exact precedents.

3.   Schumer and Wilson both said they hoped that successful testing of the new gun detectors could lead to more Congressional support for research by the National Institute of Justice.

4.   The new device relies on a technology different from the approaches used in several types of gun detectors, whose development was announced in March by the justice institute.