After I crossed the Altamont pass, just before entering Livermore, I noticed that a car in front of me was driving quite erratically, continually swerving halfway into the next lane before correcting and getting back into his own, then repeating the process in the opposite direction. I followed him at a distance for a couple of minutes to verify that this wasn't just a blip, then grabbed my phone and called 911. I gave the CHP the information I had-- black sedan, just before the Tassajara Road exit, no I can't get his plate but if the patrol car spots a PT Cruiser convertible I can point out the offending car.
I followed him, keeping my distance, as we entered a construction zone with traffic down to two lanes and Jersey barriers against the edge of the left lane. "This can't possibly go well", I thought, but somehow he managed to avoid making a mess.
Luckily the roads were mostly empty at this hour. I didn't want to risk passing him, so I stayed behind him at a safe distance and kept a very close eye on his behavior. For about 15 minutes I watched him bouncing between lanes, nearly hitting a few different cars, barely missing several medians, and constantly bouncing off the botts dots. I decided to get close enough to him that I could read his license plate number, and made a second call. This time I added the license plate number, 6NEY509 I believe, and new location information.
I kept watching my mirrors for flashing blue lights, or cars that looked like police cruisers, but no luck. As cars showed up behind me, I attempted to warn them of the dangerous driver ahead. They pretty much universally slowed down and either stayed behind him, or carefully passed him from two lanes away.
His speed was erratic-- he'd slow down to about 50mph, then speed up to 80, then drop down to 65. I maintained hope that he'd get pulled over, but no dice. We continued into Oakland. He was in the far left lane at the 980 split, so I had high hopes of losing him, but at the last minute he veered across three lanes of traffic, jumped a median (!), and swerved back and forth between lanes as he got onto the 980 connector. Dammit. I briefly considered making another 911 call, but I was almost home at this point. I took the ramp extra carefully, as it's a long swooping high-speed curve.
He got off the freeway at the 14th Street exit in Oakland, two exits before mine. I breathed a sigh of both relief and frustration when I saw that he was past the point of no return for the exit-- I was happy that he was no longer a factor for me, and that he would probably get home safely, but it was extremely annoying to realize that this fucking asshole was going to get away with endangering lives in this way.