Exhibit 4




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Westport Code of Conduct
 Letter from the CEO
    
    
    3Westport Code of Conduct
    
    
    4Introduction
    
    
    4Our Commitment to Ethical and Legal Conduct
    
    
    4Application of the Code
    
    
    5Westports Responsibilities To Its Stakeholders
    
    
    5Shareholders
    
    
    6Employees
    
    
    6Customers
    
    
    6Partners and Suppliers
    
    
    6Governments
    
    
    6Communities and the Environment
    
    
    7Employment Policies
    
    
    7A Discrimination- and Harassment-Free Workplace
    
    
    7Safety and Respect for the Environment
    
    
    8Promotion of the Health and Well Being of Employees
    
    
    8Open Communications
    
    
    9Employment Abroad
    
    
    9Business Policies
    
    
    9Integrity of Books and Records
    
    
    9Protecting and Managing Westport Assets
    
    
    9Competitive Business Practices
    
    
    10Communication with Media and Other Outsiders
    
    
    10Internal Controls and the Authority to Make Westport Commitments
    
    
    10Financial Management
    
    
    11Conflicts of Interest
    
    
    11Use of Position
    
    
    11Accepting and Giving Gifts and Benefits
    
    
    12Other Business or Employment
    
    
    12Community Involvement
    
    
    13Confidentiality and Privacy
    
    
    13Confidential Information
    
    
    13Personal Information
    
    
    14Patents and Other Intellectual Property
    
    
    14Insider Trading and Other Securities Issues
    
    
    14Monitoring and Enforcing This Code
    
    
    15Waivers of This Code
    
    
    15SCHEDULE A: Westport Compliance Certificate
    
    
    16
 Westport Code of Conduct
    
    July 2008
  - 2 -




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Letter from the CEO
     
 
 Westport Code of Conduct
    
    July 2008
  - 3 -




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Introduction
  Our Commitment to Ethical and Legal Conduct
   
    
    honest and ethical conduct, including the ethical handling of actual or apparent
conflicts of interest between personal and professional relationships;
 
    
    full, fair, accurate, timely and understandable disclosure in reports and documents
that Westport files with, or submits to, the applicable securities regulatory authorities
and other public communications made by Westport;
 
    
    compliance with applicable governmental laws, rules and regulations;
 
    
    the prompt internal reporting of Code violations to an appropriate person or persons
identified in the Code; and
 
    
    accountability for adherence to the Code.
  
    
    Is what we are proposing to do legal?
 
    
    Is it right?
 
    
    Is it fair?
 Westport Code of Conduct
    
    July 2008
  - 4 -




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
    
    Is it consistent with our mission and values?
 
    
    Could I clearly explain my decision to all stakeholders with pride?
 
    
    Would I feel proud if my actions were described in public print?
  Application of the Code of Conduct
    Westports Responsibilities To Its Stakeholders
   Westport Code of Conduct
    
    July 2008
  - 5 -




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Shareholders
   Employees
  Customers
  Partners and Suppliers
  Governments
  Westport Code of Conduct
    
    July 2008
  - 6 -




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Communities and the Environment
  Employment Policies
   
    
    Discrimination- and harassment-free work environment
 
    
    Safety and respect for the environment
 
    
    Promotion of the health and well being of employees
 
    
    Open communications
 A Discrimination- and Harassment-Free Workplace
   Westport Code of Conduct
    
    July 2008
  - 7 -




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Safety and Respect for the Environment
  Promotion of the Health and Well Being of Employees
   Westport Code of Conduct
    
    July 2008
  - 8 -




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Open Communications
  Employment Abroad
  Business Policies
 Integrity of Books and Records
   Protecting and Managing Westport Assets
  Westport Code of Conduct
    
    July 2008
  - 9 -




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Competitive Business Practices
   Communication with Media and Other Outsiders
  Internal Controls and the Authority to Make Westport Commitments
  Westport Code of Conduct
    
    July 2008
  - 10 -




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Financial Management
  Conflicts of Interest
    Use of Position
  Westport Code of Conduct
    
    July 2008
  - 11 -




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Accepting and Giving Gifts and Benefits
   Other Business or Employment
    Westport Code of Conduct
    
    July 2008
  - 12 -




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Community Involvement
  Confidentiality and Privacy
  Confidential Information
   Westport Code of Conduct
    
    July 2008
  - 13 -




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Personal Information
   Patents and Other Intellectual Property
   Insider Trading and Other Securities Issues
   Westport Code of Conduct
    
    July 2008
  - 14 -




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Monitoring and Enforcing This Code
 .
   Waivers of This Code
  Westport Code of Conduct
    
    July 2008
  - 15 -




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SCHEDULE A: Westport Compliance Certificate
        Westport Code of Conduct
    
    July 2008
  - 16 -