Hi there,

I'd like to understand better how "joint ownership" over a trademark
works, and what rights each owner has over the trademark. I'd like to
know the answer for registered trademarks, and more importantly,
common law trademark.

When I look on the internet, I see cases where companies have
joint-trademarks on a term, such as "super-hero" being owned by DC and
Marvel.

1. How to agree to joint-ownership of a mark:

In a common law trademark that is develped by the original owner by
use of the trademark nationwide, if another person wants to use the
trademark, is a written agreement between the two parties sufficient
to provide joint ownership of a mark?

I'd like to ask the same question over a federally registered trademark.

2. Legal rights to protect the trademark.

As you probably know, trademark owners have a responsibility under the
Lanham act to protect the trademark. Provided that a trademark is
jointly owned by two people, who has rights to file for trademark
violations? Do both parties have to be involed? Is it possible by the
contract to allow the new owner to take legal steps at will to protect
the mark by an infringer?

Thank you,
Alan