Interacting models involving particles with Spin >=1 are plagued with non-physical degrees of freedom and similarinconsistencies. These problems already occur when the field is coupled to an external potential and often appear in non-renormalizable models.
    String-Local fields, in contrast to the usual point-local fields, manage to avoid such problems due to better renormalizability and a fixed number of degrees of freedom but have a worse localization in exchange.    
    By rewriting a point-local model in terms of string-local fields, we can try to circumvent inconsistencies. The point-local and string-local model could for example lead to the same S-Matrix. Or, if there are deviations, they could indicate how to modify a problematic interaction to become consistent.

These possibilities are currently studied for Spin-1 and Spin-3/2 and recent results will be presented.