Ethical Disclosure of Professional Knowledge in PhD Dissertation I have just completed my PhD. Although my examiners did not raise any concerns, I have been grappling with an ethical issue for the entire duration of my candidature. 

The issue concerns professional knowledge of the field on which my research is based. This is an issue of concern because I am employed in the field and have access to information that is generally not publicly available (but is available to me as an employee) or only found in hard-to-get industry publications (e.g. newsletters). These publications are hard-to-get because of their specialised nature and limited circulation. 

Disclosing this information creates a potential conflict of interest for me (because of reasons associated with commercial-in-confidence, breach of trust etc.). It gets even worse because I am often actively involved in generating this information as part of various negotiations I am required to have with third parties (in my capacity as an employee). As an example, I draft policy speeches for my CEO so this has the effect of quoting my own work in my dissertation (but attributed to my CEO in the citation and bibliography!)  

To resolve this matter, I have declared (categorically) this conflict of interest (several times in my dissertation) (although I don't identify myself as the ghost writer). I have also put whatever information I thought could be ethically disclosed in the relevant context (e.g. cited the publicly available newsletter, where possible). This was to ensure future researchers could benefit from this 'inside' knowledge. I have stated this as one of the contributions to knowledge that my dissertation is making.

I must add that the professional knowledge does not contradict or undermine my research, so I am certainly not withholding the information for this reason. On the contrary, this information enhances the main arguments of my study (so omitting it presents a significant dilemma for me).

i would love to hear how else could this matter be resolved.
I've known cases where the thesis itself has very restricted circulation for a fixed period (e.g. six years) after completion, to protect the commercial information that went into it. The restriction also meant that papers couldn't be published on the back of the PhD research for six years, too.

That was an arrangement made early on during the writing of the thesis, and it enabled the use of a lot of information that would otherwise have been out of bounds.

That's potentially quite an impediment to one's career, so one would have to get good advice on whether it was a price worth paying. But it doesn't make an academic career impossible: I know of at least one successful academic who's take this path - she's an exceptional talent, and so it's no surprise that her path has been exceptional. It does put an emphasis on diversifying straight after the PhD, to gather material for new publications. Diversification can be a good thing: lots of new post-docs get typecast and trapped by and in their PhD subject.