Zoloft (sertraline) is an antidepressant in a group of drugs called selective serotonin reuptake inhibitors (SSRIs). The way sertraline works is still not fully understood. It is thought to positively affect communication between nerve cells in the central nervous system and/or restore chemical balance in the brain.
Montana's current nighttime speed limits are 65 m.p.h. on Interstates and 55 m.p.h. on two-lane highways, and those are not affected by the court's ruling.
The law does not allow for exceeding the posted speed limit for purposes of keeping up with traffic or for passing in any state I know of. Here in Arizona the courts are upholding more than 3 mph over the speed limit, and even 1 over either statutory limit: 15 mph in school zones or 75 mph anywhere in the state.