The concept of good faith pretty much underpins employment agreements world wide; whether it is provided for in the country's respective employment legislation (such as New Zealand and Australia), or is implied by the act of entering into an employment contract.
Employers can often struggle with the concept of good faith, as many times the requirement to act in good faith generally occurs where the employer needs to make a "business decision" (such as restructuring, redundancy, poor performance etc), and the employees are a secondary component in the equation. Generally in instances such as this, the businesses may seek legal advice, either through their in house HR team or at times independently.
Lawyers have a very specific purpose in this process, and that is to provide legal interpretation around the tolerance for the employer to act within that is provided for in the respective legislation, and to provide legal council and representation should it all go pear shaped.
What lawyers generally are unable to do is to provide the moral and ethical aspects around what good faith means, and this is where your HR partner should be able to step up and assist. A good HR partner should not only be able to advise the employer of the legal implications of what the business is attempting, but should be able to bundle this up within the aspects of what good faith should provide for.
Seeking HR advice at the start means that a business can not only have a higher level of flexibility in the execution of business decisions, with less costs associated for procedurally deficient processes; but can still deal with its employees in a legal, ethical and moral capacity.
Not a "tea and tissue" HR person, I actually believe that HR can provide strategic advice of value to an organisation. Not only do I believe HR can, but I actively work to do so.