UCMJ
3-105. Wearing Army uniforms is prohibited in the following situations:
In connection with the furtherance of any political or commercial interest, or when engaged in off duty civilian employment.
When participating in public speeches, interviews, picket lines, marches, rallies, or public demonstrations, except as authorized by competent authority.
When attending any meeting or event that is a function of, or is sponsored by, an extremist organization.
When wearing the uniform would bring discredit upon the Army.
When specifically prohibited by Army regulations.