Haystack, an app that allows users to hand off parking spaces that they occupy for a $3 fee, planned its launch today in Boston despite the fact that the City of Boston is none too pleased that the company is selling a good that they don’t actually own. (See update below.)

Last week, a spokeperson for Mayor Martin J. Walsh—a supporter of using innovation to improve the city and lives of its citizens—said that Haystack is “not in line with the city’s effort to keep parking as open and publicly accessible as possible.”

Now Walsh has released a statement in regard to “pay-to-park” apps:

“The Boston Transportation Department (“BTD”) welcomes innovation in all aspects of urban transportation, including the use of apps by smartphone users. BTD is excited to pursue new methods of easing congestion and promoting green alternatives for all those who live and work in the Boston area. Such methods, however, must not interfere with the public’s right to access public resources, including parking. “Pay-to-park” apps may impede access to public parking spaces.” “By inviting users to transfer the occupancy of a particular parking space for a fee, these apps may subject public spaces to private regulation. Use of these apps while searching for a parking space may also lead to distracted driving.” “BTD, the entity with exclusive statutory authority to regulate the flow of traffic and manage parking in the City of Boston, ensures fair and equal access to public resources. As such, BTD will continue to evaluate any and all systems that may infringe upon the public’s right to equal access and/or those that may artificially inflate the cost of spaces on Boston roadways and in municipal off-street parking lots, and BTD will take appropriate measures to prohibit any such app that is determined to do so.”

Parking apps like Haystack have increasingly come under pressure from local governments. The City of San Francisco recently forced parking app MonkeyParking to shut down its service over the weekend, and more and more apps that sell city-owned parking spaces for a fee are coming under scrutiny throughout the country.

Tonight, I will be sitting down with Haystack founder and chief executive Eric Meyer who is in town to celebrate the launch of Haystack in Boston and report his thoughts on the issue tomorrow.

Update: Haystack has pushed back its planned launch of the app to Thursday.