I'm glad to see we agree on something. Yes the NYDMV has assumed the role of the state legislature. It exceeded it's authority. As I've stated many times on this forum: Rules that directly affect people lives should be voted on by the state legislature and not by some bureaucrat.
Let me be clear on this: I’m not saying I agree with Sill’s argument that the DMV exceeded its authority. I have no position on that either way as I have not fully researched NY law on that. Three of five judges in the lower appellate court rejected that argument so it is far from clear that it is a winner.
It has long been the case that administrative agencies may issue regulations that have the effect of law so long as that power was granted to them by the Congress (for federal agencies) or the state legislators (for state agencies). That is not undemocratic because the legislators, who were elected by the people, agreed to let the agency issue those regulations and the legislature retains the power to revoke or modify any agency regulation it does not like. I have on my desk thousands of pages of federal tax regulations issued by the U.S. Treasury. Congress did not expressly vote on each of those regulations. But they are nonetheless valid and courts will enforce them because Congress gave the Treasury the power to issue those tax regulations. This kind of power to issue regulations is necessary because Congress and the state legislatures do not have the time nor the technical expertise to issue rules in the kind of detail that is necessary, but administrative agencies do have the expertise and time to do that work.
The issue with any agency regulation when looking at validity generally comes down to examining three things: (1) did the agency exceed the scope of the authority the Congress or state legislature gave it; (2) did the agency fail to follow the proper procedures in issuing the regulation; and (3) does the regulation violate either the federal or state constitution or other applicable law? If the answer to any of those is yes then the regulation won’t be valid. But the answer to each is no, the regulation is very likely going to be upheld.
The point here is that every rule we live by does not have to voted on by a legislature to be valid, even those that have a direct affect on people’s lives. The law allows for agency regulations. They are a necessary part of government operation in our complex society. The legislatures simply cannot do it all themselves.