I have a new product that serves the same purpose as my competitor's long-standing product. One thing I have considered doing is allowing my program to import document files created by their product in order to provide an easy way for users to migrate towards mine. Naturally, this would be done without the competitor's permission, as it goes against their interests.

I've seen this done before with office suite software (e.g. Open Office and Apple Pages can import MS Word documents), but I'm wondering if there are any concerns, legal or ethical, with me doing this.

I fully expect any answers will most likely fall under the "I am not a lawyer" clause, but it would be helpful to have a starting point for anything I would need to be aware of, or if I shouldn't need to worry.