Legal Question in Real Estate Law in California

Only your brother's interest can be seized. The practical effect is that you may end up with a co-owner who isn't your brother. Being a co-owner with a stranger is generally an awkward situation, so one or the other of you would probably end up either selling to the other, or jointly agreeing to put the property up for sale, or, failing some kind of agreement, one or the other of you could sue for partition. Partition involves a court-ordered sale and fair division of the net proceeds of sale.

I might add that half interests in real estate, when owned by strangers, are generally not much in demand nor worth half the value of the property if 100% owned, so perhaps the law-enforcement agency would be somewhat reluctant to seize a half interest (which is all they could seize).

In any event, your ownership interest is not subject to seizure, but you could end up with a co-owner who isn't your brother. See Grothe v. Cortlandt Corp. (1992) 11 Cal.App.4th 1313; Rupp v. Kahn (1966) 246 Cal.App.2d 188; and McCauley v. Fulton (1872) 44 Cal. 355.