The main problem is that there needs to be a judicial determination as to what of the marital estate is community property and what is separate property.
A person can only devise what they legally own. An earth-shattering concept, I know. If an item is considered community property, e.g. a house, then one spouse may only unilaterally devise up to 50% of the home. If the spouse tries to devise more than 50% of the home, the other spouse can validly object.
Conversely, a spouse is free to devise all of their separate property as they see fit. If the marital home is found to be separate property, then the spouse may leave the house to whomever they please and the other spouse cannot object.
When making property characterizations, dates are of optimal importance. For example, prior to being married, any property acquired would be the acquiring spouse's separate property. See Family Code § 770. During marriage and subject to certain exceptions, property acquired then is considered community property. See Family Code § 760. Following the "date of separation" any property acquired after that is considered the acquiring spouse's separate property. See Family Code § 771. In short, there are three phases: (1) pre-marriage, (2) marriage and (3) post-separation.
The following hypothetical illustrates the different stages of property acquisition.
Hal and Wendy began dating in 2012. Hal was reluctant to marry Wendy because Wendy's parents did not approve of Hal's occupation, a medicinal marijuana dispensary owner. In late 2012, Hal purchased in his name alone an investment property, a duplex, in Santa Cruz, CA. Eventually Hal proposed to Wendy and the two eloped on January 1, 2013 in California. Following their secret marriage, the newlyweds jointly purchased a condo in San Francisco, CA. Hal also used his earnings at the time to pay the duplex's mortgage. When recreational marijuana use became legal in Colorado on January 1, 2014, due to passage of Amendment 64, Hal stated his intentions to divorce Wendy and move there. So on January 2, 2014, Hal packed all of his belongings and moved to Boulder, CO permanently. Wendy then filed for divorce in San Francisco County. Wendy subsequently drowned her sorrows by buying thousands of dollars in jewelry. The divorce was finalized in summer 2014.
For characterization purposes, the Santa Cruz duplex is both separate property, as it was purchased before marriage, and community property as well, since Hal used marital wages to reduce the mortgage. See Marriage of Moore (1980) 28 C3d 366, 371/ Marriage of Marsden (1982) 130 CA3d 426, 439. The San Francisco condo is community property because it was purchased during marriage. The jewelry is Wendy's separate property because it was acquired after the date of separation.
For estate planning purposes, Hal can only unilaterally devise a fraction of the Santa Cruz condo. Similarly, Hal and Wendy can each only unilaterally devise a fraction of the San Francisco condo. However, Wendy can do as she pleases with the jewelry.
