Noncommercial Signs, Posters, Flags, or Banners Statute
(a) The governing documents may not prohibit posting or displaying of noncommercial signs, posters, flags, or banners on or in a member's separate interest, except as required for the protection of public health or safety or if the posting or display would violate a local, state, or federal law.
(b) For purposes of this section, a noncommercial sign, poster, flag, or banner may be made of paper, cardboard, cloth, plastic, or fabric, and may be posted or displayed from the yard, window, door, balcony, or outside wall of the separate interest, but may not be made of lights, roofing, siding, paving materials, flora, or balloons, or any other similar building, landscaping, or decorative component, or include the painting of architectural surfaces.
(c) An association may prohibit noncommercial signs and posters that are more than nine square feet in size and noncommercial flags or banners that are more than 15 square feet in size.
Added August 2020
Specifically, California Civil Code section 4710 provides as follows:
(a) The governing documents may not prohibit posting or displaying of noncommercial signs, posters, flags, or banners on or in a member's separate interest, except as required for the protection of public health or safety or if the posting or display would violate a local, state, or federal law.
(b) For purposes of this section, a noncommercial sign, poster, flag, or banner may be made of paper, cardboard, cloth, plastic, or fabric, and may be posted or displayed from the yard, window, door, balcony, or outside wall of the separate interest, but may not be made of lights, roofing, siding, paving materials, flora, or balloons, or any other similar building, landscaping, or decorative component, or include the painting of architectural surfaces.
(c) An association may prohibit noncommercial signs and posters that are more than nine square feet in size and noncommercial flags or banners that are more than 15 square feet in size.
Flag Statute
California Civil Code section 4705 has similar provisions with respect to the flag of the United States:
(a) Except as required for the protection of the public health or safety, no governing document shall limit or prohibit, or be construed to limit or prohibit, the display of the flag of the United States by a member on or in the member's separate interest or within the member's exclusive use common area.
(b) For purposes of this section, “display of the flag of the United States" means a flag of the United States made of fabric, cloth, or paper displayed from a staff or pole or in a window, and does not mean a depiction or emblem of the flag of the United States made of lights, paint, roofing, siding, paving materials, flora, or balloons, or any other similar building, landscaping, or decorative component.
(c) In any action to enforce this section, the prevailing party shall be awarded reasonable attorney's fees and costs California Civil Code section 4705