MA Unsafe Lane Change - MGL 89-4

[MetalWanderer]

What is the name of your state (only U.S. law)? Massachusetts

Hi Everyone,
This morning while I was driving my housemate to work, I received a citation for an "unsafe lane change" and am considering challenging this in court. While general advice about what kind of defense to present would be appreciated, my question is specifically about the law he cited.

The facts: Travelling on I-91S in Springfield, MA. I take the exit for I-291E, which loops around to the left, and merges with two lanes that come in from the right. I need to take the exit immediately after the merge (looks like about 1000ft merge-to-exit on Google Maps), so I put on my turn signal and match the speed of the traffic to my right. I see a good spot behind a minivan, look to my right, and slowly pull in behind it. I need to immediately go over another lane to my right, so as I'm completing the lane change, I'm watching in my right wing mirror. Just as I finish the (first) lane change, suddenly there's a trooper right on my ass. Oh crap. The rest proceeds as you might expect and without anything noteworthy. The fine is $100.

On my citation, he wrote "89-4" in the "Chap/Sec/Sub" field and "Unsafe Lane" in the description. Searching around for the text of the law leads me here: [url=http://www.mass.gov/legis/laws/mgl/89-4.htm]M.G.L. - Chapter 89, Section 4[/url]

My question: The way I read this law, it has nothing to do with the situation I was in. My view was not obstructed, I was not a slow moving vehicle, and I was not on a hill. In fact, I can't seem to find ANY Massachusetts law that mentions the phrase "unsafe lane change" or anything to that effect. Is this law relevant in this case? Can I claim he cited the wrong law? How powerful is this as a defense?

[mattsp]

It is likely you were cited for ch89 s4a which reads as follows:

Chapter 89: Section 4A. Driving vehicles in a single lane; motorcycles, riding and passing


Section 4A. When any way has been divided into lanes, the driver of a vehicle shall so drive that the vehicle shall be entirely within a single lane, and he shall not move from the lane in which he is driving until he has first ascertained if such movement can be made with safety. The operators of motorcycles shall not ride abreast of more than one other motorcycle, shall ride single file when passing, and shall not pass any other motor vehicle within the same lane, except another motorcycle.


[url=http://www.mass.gov/legis/laws/mgl/89-4a.htm]M.G.L. - Chapter 89, Section 4a[/url]