SCSC - Group: Assurance cases

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The Assurance Cases Working Group (ACWG) has been established to provide guidance on all aspects of assurance cases including construction, review and maintenance.

  • It is intended that this will be broader than safety and will address interaction and conflict between related topics.
  • This will address aspects such as proportionality, rationale behind the guidance, focus on risk, confidence and conformance
  • An important aspect under consideration is the role of counter argument and evidence and the treatment of potential bias in arguments

One of the working groups initial activities is to take on board the maintenance of the Goal Structuring Notation (GSN) Community standard.  See for further details.

Please contact Phil Williams (using link on 'Groups' main page) if you are interested in the activities of this working group and would like to make an active contribution to its work, or would simply like to be kept informed of the group's activities. 

- Participants need to be registered with the website (this website)

- Participant agree to work to the group's Terms of Reference (

WG Lead Bio

Phil Williams is an independent system safety consultant having started his own consultancy in 2013 after 27 years with General Dynamics UK, where he held the role of Chief Safety Authority. He is a Chartered engineer and Fellow of the IET.

Phil is a member of the SCSC Steering Group and is the chair of the Assurance Case Working Group which includes responsibility for Maintenance of the Goal Structuring Notation (GSN) standard. He is also an active member the BSi GEL65/1 committee; the IEC TC65A MT61508 (developing edition 3 of IEC 61508) and is the deputy-convenor of IEC TC65A WG18 acting as the principal UK expert in the development of the system safety standard for Defence Systems (IEC 63187). He has recently joined the ISO JTC1/SC5 committee to represent interest in the ISO15026 seriese of standards, including part 2 that addresses Assurance Cases. He has supported a number of cross-industry system safety initiatives and has represented UK defence industry on the MOD’s Safety Standards Review Committee and was a core member of the Def Stan 00-56 Issue 5/6 and Def Stan 00-55 Issue 3 authoring teams.

Phil can be contacted at

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