Lasers for defense applications continue to grow in power and fill in new portions of the spectrum, expanding the laser eye safety hazard, particularly to aircrew and aviation safety. The Laser Event Recorder Program within Naval Air Systems Command (NAVAIR) seeks to develop a low cost, self-contained laser sensor able to detect, warn and record laser exposures that hazard aircrew vision. The spectral and temporal range of hazardous lasers (400 to 1600 nm and pulsed to continuous) has presented a challenge in the past. However, diffractive optics and imaging technologies have enabled a solution to this growing threat. This paper will describe the technical requirements for the Laser Event Recorder, which are based on ANSI Z136.1 laser safety standards and common to its use on any platform. To support medical and operational laser eye protection, the LER extracts and records laser wavelength, radiant exposure, exposure duration, pulse structure, latitude, longitude, altitude and time of laser exposure. Specific performance and design issues of the LER prototype will be presented in a companion paper. In this paper, fundamental challenges to the requirements encountered during the first two years of research, development and successful outdoor testing will be reviewed. These include discrimination against all outdoor light levels and the impact of atmospheric beam propagation on accuracy of the radiant exposure determination. Required accuracy and response time of the determination of whether a laser exposure exceeds the maximum permissible exposure (MPE) will be described. Ongoing efforts to coordinate laser exposure reporting and medical management will also be discussed.