If I quit because of intolerable conditions in my workplace, can I treat it as if I was fired?
Most states recognize constructive termination of employment and treat it similarly to an actual firing. For example, if the employer reduces your wages from $12 per hour to $6 per hour, switches your day hours to the moonlight shifts, and changes your position from secretary to a janitor or vice versa, that would clearly be a constructive termination.
An employee in a state that recognizes constructive wrongful termination does not have to be fired in order to have the ability to sue an employer for intolerable working conditions. If an employee can prove that she/he was reasonably compelled to leave the job, and that these conditions were known by the employer, or intentionally created by the employer, then the employee may pursue a constructive wrongful termination action.
The remedies available in a successful constructive wrongful termination action are similar to those in a suit due to actual wrongful termination. Even if you are an at-will employee and so can be let go for no reason at all, you could file a claim for unemployment insurance based on your constructive discharge.