A tenant’s credit score is not impacted by an eviction lawsuit. When a landlord obtains a credit report from a tenant screening service such as RealSerious.com that uses official consumer credit data, the algorithm used to generate the three digit score will not factor any eviction data into the equation.
The interesting thing to note, though, is that many apartment communities don’t bother filing evictions (if possible) because of the cost, time, and lack of reporting. Instead, if a tenant defaults on the rent or causes damage and skips out in the middle of the night, the apartment community will simply file a collection account. They can do this directly (if large enough) or assign/sell it to a collection agency with very little effort.
Unlike an eviction, the collection account will show up on the tenant’s credit report and have a negative impact on the credit score for a quite a while. Three digit scores (such as the famous FICO model) take a big hit, dropping ten’s of points.
So every tenant should avoid being delinquent (or violating any other terms of tenancy). It’s always best to communicate with your landlord if there is a problem and reach an agreement if you need to terminate tenancy early.