The jury bought into the Gaye's attorney's arguments that they should consider a "constellation" of features when comparing the two songs. This legal standard will likely be challenged on appeal because it deviates greatly from previously established case law. Prior song copyright cases had used melody and lyrics as the two decisive factors, either one of which could be sufficient to render a work a copyright infringement.
Some examples of successful previous lawsuits:
In contrast, previous lawsuits that had claimed infringement due to style, chord changes, or other factors often failed. A famous example of this is the 1985 lawsuit Fantasy, Inc. v. Fogerty where Saul Zaentz of Fantasy Records sued John Fogerty on the grounds that his 1985 solo hit The Old Man Down the Road sounded similar to the 1970 Creedence Clearwater Revival song (that Fogerty also wrote) Run Through the Jungle.
Juries are inherently unpredictable and this particular Blurred Lines case was further muddied by a counter suit and odd testimony by Robin Thicke that he had been too drunk and high to write Blurred Lines. Not wanting to rely on a jury's interpretation is why most copyright cases are settled out-of-court.
To my mind, this was the second recent copyright case that marks a disturbing trend. Tom Petty claimed ownership of a chord progression from I Won't Back Down and challenged Sam Smith about his song Stay With Me. This was settled out of court so is not an official precedent, but a chord progression, like a beat, bass line, tempo, or other song feature, has not previously been held able to be copyrighted.
As I once heard someone remark, "If you could copyright a bass line or a rhythm pattern, Willie Dixon and Bo Diddley would be as rich as Bill Gates." Unfortunately, the law may be shifting in that direction.