From what I've seen and heard, the argument over the Pre-employment polygraph's validity has been around for a long time and still, nothing has changed.

Unfortunately, for the members of this site, the public perceives polygraphs as being totally accurate and therefore, any attempt to convince the government to stop using polygraph's because of their validity will probably fall on deaf ears.

Here's another approach.  First of all, it should be determined why Law enforcement agencies use pre-employment polygraphs.  I assume the answer they will give is that it is a way of screening applicants to ensure no unsavory individuals get hired as law enforcement officers.  If this is true, then someone should attempt to study if the use of polygraphs has in any way contributed to this goal.  Has anyone studied if there has been any decrease in the percentage of law enforcement officers that have been implicated in any wrong-doing after the use of polygraphs has become policy?  While you will probably not be able to convince the government to stop using polygraphs based on their validity, you might be able to show that polygraphs, which are unquestionably invasive, have not reduced the incidence of corruption or wrong-doing in law enforcement agencies.  Polygraphing costs money- agencies have to train and pay polygraphers and these same agencies lose money when applicants, that have gone through a lengthy process, get disqualifed based on a polygraph.  If it can be shown that polygraphs have in no way reduced incidences of wrong doing in an Agency, it can be argued that polygraphs are not fiscally worthwhile. Basically, attack the issue as being a waste of money.