In this kind of sentence, it's possible to use both the present and past tense. The simple present "... that employees are able to sue" means the court decided that employees are always able to sue the employer for work-related accidents. The simple past "... that employees were able to sue" means that employees were able to sue the employer for work-related accidents when the lawsuit was filed. The law might have changed since then, however.
I'd develop the sentence a bit by adding "the employer for work-related accidents" after "sue", unless that's already been discussed in a prior sentence.
Whether the sentence content is adequate depends on the context, i.e., what the rest of the discourse says. The grammar is no problem.