What is the "legality"  of a married man changing the title on the
home or other community-owned real property from "Community Property"
or "Joint Tenancy"  to a designation of "sole and separate property of
a married man"  without getting a divorce, without the previous title
being from separate legal incomes such as inheritants, etc.  This has
happened many, many times in Rohnert Park, Sonoma County, California.

Hello.

A change (or "transmutation") of real property from community property
to separate property without the consent of the other spouse would NOT
be valid.

From the Section 852(a) of the Calfornia Family Code, as listed on the
web page Divorce Source:
 
"852. (a) A transmutation of real or personal property is not valid
unless made in writing by an express declaration that is made, joined
in, consented to, or accepted by the spouse whose interest in the
property is adversely affected."

For more information visit:
http://www.divorcesource.com/CA/CODE/850_853.html

Note that Section 852(e) indicates that this rule wouldn't apply to
transfers made before January 1, 1985.
 
Alse see this document entitled "Transmutation of Community Property"
from stjames-law.com :
http://www.stjames-law.com/files/pdf/Transmutation_Of_Community_Property.pdf
 (PDF format, so you'll need the Adobe Acrobat reader if you don't
already have it http://www.adobe.com/products/acrobat/readstep2.html )
search terms: "community property", california, real property,
transmutation
I hope this helps. Note the disclaimer below that this is general
information and not intended as a substitute for professional legal
advice.