Read the sentence.

the criminal justice system is like a scale that weighs the evidence for guilt and innocence.

the statement is an example of

This is an example of a metaphor.

Explanation:

A metaphor is a comparison of two unlike things without using like or as.  The justice system is being compared to a scale.  It further explains what a scale is.  This is most likely why a scale is symbolic of court.

where are the multiple answers?

taking into account that a theme is the central topic a text treats and can be developed through a story, play, poem etc. the following are themes that can be further developed:  

my best friend jeffrey has many unusual interests. (the story could be about each of the unususal interests)

once a man gives his soul over to evil, he can never go back. (this could be a saying or a proverb)

the three sheepdogs lay around the yard all day. (it could be developed detailing how each of these sheepdogs lay around)

a priest's collar has an unusual effect upon people. (it could be developed detailing the different effect upon people)

innocence is a powerful force in a world full of corruption. (it could be developed detailing how is a world full of corruption)

king lear is a play shakespeare wrote later. (it is just a sentence and doesnt give any idea or topic to be discussed in details.

evil often wears the disguise of innocence. (this could be a saying or a proverb)