New York Times Article on Russian Harcker’s Arrest

There is maybe nothing new about governments protecting their national hackers but this is a good example on how a hacker can openly operate in his own country and then get caught in another.
The article below also makes reference to an earlier case where a Russian hacker was lured to the USA and arrested through evidence gathered by the FBI hacking his computer back own.
I have always wondered how could such evidence stand in court, what would stop the FBI to plant some fake evidence?? How is hacking into the computer located in a different country be legal either?

Hacker’s Arrest Offers Glimpse Into Crime in Russia