Erroneous

adjective

1. Containing an error; inaccurate.

   "His answer to the sum was erroneous."

2. Derived from an error.

   "His conclusion was erroneous, since it was based on a false assumption."

3. Mistaken.

   "Her choice at the line-up proved to be erroneous, as she had only seen the mugger for an instant."

4. Wandering; erratic.
5. Deviating from the requirements of the law, but without a lack of legal authority, thus not illegal.