This story should be of interest to you:
RALEIGH -- David N. Cox says he was merely exercising his right to petition the government, but a state Department of Transportation official has raised allegations that Cox committed a misdemeanor: practicing engineering without a license.
Cox and his North Raleigh neighbors are lobbying city and state officials to add traffic signals at two intersections as part of a planned widening of Falls of Neuse Road.
After an engineering consultant hired by the city said that the signals were not needed, Cox and the North Raleigh Coalition of Homeowners' Associations responded with a sophisticated analysis of their own.
http://www.newsobserver.com/2011/02/...-on-state.html
I have given many highly technical critiques of engineering projects in my area, for instance the door-zone bike lanes recently installed on Hillsborough Street in Raleigh. Oftentimes I include scale diagrams and make recommendations of alternative designs. I am an engineer myself, but not a PE, and I am careful to represent myself as a citizen advocate or bike club representative and not a PE. Since the above story came out, I have started putting explicit disclaimers on my communications where I make engineering critiques. But I have always found that being respectful toward the local engineers gets me a lot of access and opportunity to provide input and affect their decision making. They call or email me for advice, bribe me with drinks, etc.
There are many bikeway advocates, planners, and landscape architects who are not engineers but publish extensive documents advocating specific engineering treatments even though the authors don't have a PE, or in most cases, any engineering degree. Oftentimes, it shows in their work, for instance where they fudge vehicle widths to make it look like cyclists will have more room in the door zone bike lane than they actually will. But I think it's better to eviscerate their bad designs with better engineering arguments and quantitative evidence rather than to try to muzzle speech.