In the last two election cycles, in both major parties, presidential candidates and the press have argued over the timeliness and completeness of the release of personal tax returns.  This year, the disagreement has taken a new turn with the possibility that one of the candidates will not release his filings at all.  Editorialists have argued for compliance with the “norm” of disclosure that has been observed for decades.  John Wonderlich of the Sunlight Foundation questions why release is just a "norm" and not a legal requirement, and he argues for a new law.

That the release of taxes remains a norm and not more may be explained by a number of factors.  For elected officials, there's always the fear that there is no stopping point.  If Congress were to mandate the release of returns by presidential candidates, the question would naturally turn back on them--why they would not put themselves under the same obligation.  Gradually other elected officials might feel the same pressure, which could eventually also influence the judgment about whether the returns provided by senior government officials during the vetting process should also be subject to public disclosure.  To keep a norm a norm is to keep the underlying transparency expectation within limits and to leave issues of compliance to public debate and judgment.  It serves also to maintain a balance between exposure of this information some of the time, in a narrow set of circumstances, but only by public expectation and political choice, preserving the overall principle of privacy.

There may still come a tipping point when the norm is deemed insufficient and a legal requirement is put in its place.  It is hard to say when that point might be reached.