Ask a Trooper - When to signal a turn
Question: How far ahead of time are you required to signal a turn and is there a time when drivers can legally turn left on a red light after stopping (like they do on right turns)?
Answer: For the first question, Minnesota law requires you to signal at least 100 feet before a turn. A turn would include a lane change or other change of course.
For the second question, yes, believe it or not, there are times when a driver can legally turn left on a red arrow (but like you said, only after stopping) like they do on right turns.
Let me explain those instances. My translation of the law in one instance is when a motorcyclist fails to get a green arrow because the sensors failed to pick up the motorcycle and they sat through a couple red lights without getting the green arrow, or the signal is malfunctioning and it's obvious that they are not going to get a green arrow. If that happens, the motorcyclist can make that left turn on a red arrow when it is safe and clear to do so and there is no sign prohibiting it, but only after coming to a complete stop first and waiting through a couple light cycles to be sure that they are not getting a green light. They cannot just come up to any red arrow and then turn after stopping, or even "rolling" through the stop light. I have seen that happen. That's against the law and they will be charged for running a semaphore if they do that.
Another instance is when you are driving any vehicle from a one-way street to another one-way street requiring only a left turn. In that case, if the motorist stops, and there is no traffic, and there is no sign prohibiting the left turn on a red light, then a left turn can be made from that one-way road onto the other one-way road.
I am personally not aware of any other instances that left turns can be made on red lights.
If you have any questions concerning traffic-related laws in Minnesota, send your questions to Trooper Jesse Grabow, Minnesota State Patrol, 1000 Highway 10 West, Detroit Lakes MN 56501-2205. Or reach me at firstname.lastname@example.org.