Yes, law enforcement fabricates evidence, because they fake the evidence in order to make sure that they win the case. There is a reason that cops are so opposed to the little people being able to take video of their stops. They are thugs and bullies who became professional thugs and bullies.
I believe some people in law enforcement do fabricate evidence. I know one officer pulled me over and insisted I ran a red light and he knew this despite his location at the opposite side of the intersection. There are many other cases being related on the Internet of much worse scenarios. With power comes corruption.
Yes, I do think that law enforcement can fabricate evidence. I think it happens a lot in our society. Law enforcement is the most corrupt institution in our society and their a lot a pressure to get your man, that's why I believe it causes a lot of underhanded things to happen.
Although there are some cases where law enforcement has fabricated evidence this is not a common occurrence. Most officers would not want to risk their jobs by doing something that is illegal and with today's technology it would not be difficult to find out which evidence has been fabricated. They also have to follow a chain of command which is highly regulated so this doesn't happen.