This SAE Aerospace Information Report (AIR) addresses legal issues concerning use of non-deterministic methods in the design and/or analysis of systems. The investigation includes an assessment of legal precedent for use of these methods both in the aerospace industry and in other non-aerospace engineering contexts. The investigation is primarily, but not exclusively, focused on United States of America Federal and State Law.

This document is not intended to be used in any way as a "legal justification" for the use of Probabilistic Methods - it is simply a compilation of experience and past precedent.

Many engineers note that the use of Probabilistic Methods for failure risk assessment implies an acceptance that any design will have a finite, albeit small, risk of loss of function, and express concern that this could be seized upon in a Court of Law to indicate that the design was "unsafe". This report helps to allay some of these fears by presenting the logic used in past legal determinations to assess liability following loss of function of artifacts designed using both deterministic and probabilistic engineering methods.

Some recommendations are also provided in the report of "good practice" to be followed when using non-deterministic design methods - most of which are equally applicable to deterministic design methods.

Description of Contents:

This Aerospace Information Report has been compiled from three basic sources:

a. A presentation given at the Spring, 1998 meeting of the SAE G-11 Probabilistic Methods Committee in Scottsdale, Arizona. The presentation was prepared by the "Legal Issues" group of the "Issues" Subcommittee, and was based on a literature search performed during 1997 and early 1998. Section 2 of this report is a summary of this presentation.

b. A study of legal issues surrounding the implementation of Probabilistic Methods, funded by SAE and performed during the Summer of 1998 by Mark S. Paxton, a research student at the University of Dayton School of Law. Section 3 of this report includes a summary of the findings of this study, and the full study report is provided in Section 6 as attachment 2 to this AIR.

c. A study of legal implications of Probabilistic or Deterministic Risk Assessment Engineering, funded by SAE and performed during the Fall of 1998 by Zhaoyang Li, a research student at Vanderbilt University School of Law. Section 3 of this report includes a summary of the findings of this study, and the full study report is provided in Section 6 as attachment 3 to this AIR.