Other than sporting a more pronounced philtrum, the Van Beuren Studio's Milton and Mary Mouse were dead ringers for Disney's more famous Mickey and Minnie. Take a look at this 1930 cartoon, "The Office Boy," and you'll understand why sue-happy Disney went after Van Beuren.
After Disney filed a lawsuit in 1931, Amedee J. Van Beuren issued the following statement:
"The only information we have thus far received that such action is pending is contained in articles in the papers. In my judgment the action is entirely without merit or foundation. Aesop's Fables created the characters Milton and Mary Mouse at the inception of the company in 1921 and the company has been using them.
"If there has been any imitation, it would appear to be at the door of Walt Disney Productions, whose characters of Mickey Mouse and Minnie Mouse are so similar to ours. As soon as we are served with papers we shall be prepared to defend the action."
"Van Beuren forgot to mention that the characters had been recently re-designed by John Foster to significantly resemble the Disney characters." notes Animation Anecdotes. "Milton had appeared a year before in The Polo Match (1929) but looked more like a small rat in that film.
By the end of the year, a federal court issued a decree prohibiting Van Beuren Studio from using "Mickey Mouse" or any representation of the character that could be easily mistaken or confused with Disney's "Mickey Mouse."