There are witnesses and the jury evaluates them.

The relevant section from the article

>“In addition to Mr. Diaz, three other witnesses (all non-Tesla contract employees) testified at trial that they regularly heard racial slurs (including the n-word) on the Fremont factory floor. While they all agreed that the use of the n-word was not appropriate in the workplace, they also agreed that most of the time they thought the language was used in a ‘friendly’ manner and usually by African-American colleagues.”

This is a civil case. Juries are only for criminal cases.

Juries are common in civil trials in the US.

> In Suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law.

7th amendment says otherwise.