As it turns out, under Federal Trademark Law the marks in question should never have been issued in the first place. The
Lanham Act 15 U.S.C. §1052(b) provides that any mark that consists of or comprises the flag of any foreign nation cannot be registered as a trademark. It is non-ambiguous.
“No trademark by which the goods of the applicant may be distinguished from the goods of others shall be refused registration on the principal register on account of its nature unless it … (b) Consists of or comprises the flag or coat of arms or other insignia of the United States, or of any State or municipality, or of any foreign nation, or any simulation thereof.”
The flag of the Netherlands is a tricolor flag of red-over-white-over-blue horizontal bars (depicted below). Variants of the flag have been in use since 1572 and in 1937 the flag was officially formalized as the national flag of the Netherlands. It is the oldest tricolor flag in existence and it far predates the use of the red-over-white-over-blue horizontal bars by RE/MAX.RE/MAX’s trademarks (registration numbers 1,702,048 and 1,691,854) are both marks that “consists of or comprises the flag or coat of arms or other insignia of the United States, or of any State or municipality, or of any foreign nation, or any simulation thereof”, specifically, the flag of the Netherlands, and under the statute “shall be refused registration on the principal register on account of its nature”.