In this article about drivers who won’t get the fuck out of the left lane if traffic is backing up behind them, there are difference in opinion. There are drivers who won’t get out of the way, and those who would like for those drivers to get out of the way. As it is, states’ rights prevails and so each of the 50 states has different laws about driving in the left lane. In some states, you cannot hold up traffic in the left lane. In some you can. Some states allow drivers to cruise in the left lane, some don’t.
In Washington state, it is illegal to hold up traffic in the left lane, even if you are doing the speed limit (ranges 55 – 75 miles per hour there). According to the state trooper interviewed for the article, you are breaking the law if you are driving the speed limit and holding up traffic. That means of course that the speeders in the left lane are legal and the son ofa bitch who won’t get out of the way is the lawbreaker.
So, it is illegal to drive the speed limit if you are holding up speeders. At the same time, I assume that it is illegal to drive faster than the speed limit (accepting that the cops will give you a buffer). So it is illegal to speed and not speed at the same time, in the left lane.
Actually if you really want to drive fast around Seattle, you can pay for the privilege. Some of the freeways in King or Pierce County allow you to pay a toll to drive in an inside lane that’s cleared of traffic.