DMV網站上關於居民和非居民的解釋，如果被認定是加州居民，必須10天內取得
加州駕照，不能採用台灣駕照＋國際駕照的模式。

How to apply for a driver license if you are over 18

If you are a visitor in California over 18 and have a valid driver license
from your home state or country, you may drive in this state without getting
a California driver license as long as your home state license remains valid.

If you become a California resident, you must get a California driver license
within 10 days. Residency is established by voting in a California election,
paying resident tuition, filing for a homeowner’s property tax exemption, or
any other privilege or benefit not ordinarily extended to nonresidents.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

http://www.dmv.ca.gov/dl/dl_info.htm
從這個部分來看，大部分留學生都可使用本國駕照。

Residency

12505.  (a) (1) For purposes of this division only and notwithstanding
Section 516, residency shall be determined as a person’s state of domicile.
"State of domicile" means the state where a person has his or her true,
fixed, and permanent home and principal residence and to which he or she has
manifested the intention of returning whenever he or she is absent.

Prima facie evidence of residency for driver’s licensing purposes includes,
but is not limited to, the following:

(A) Address where registered to vote.

(B) Payment of resident tuition at a public institution of higher education.

(C) Filing a homeowner’s property tax exemption.

(D) Other acts, occurrences, or events that indicate presence in the state is
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
more than temporary or transient.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

http://www.dmv.ca.gov/pubs/vctop/d06/vc12505.htm
這個部分看起來，(D)比較有爭議些。


Resident

516.   "Resident" means any person who manifests an intent to live or be
located in this state on more than a temporary or transient basis. Presence
                                                                   ^^^^^^^^
in the state for six months or more in any 12-month period gives rise to a
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
rebuttable presumption of residency.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following are evidence of residency for purposes of vehicle registration:

(a) Address where registered to vote.

(b) Location of employment or place of business.

(c) Payment of resident tuition at a public institution of higher education.

(d) Attendance of dependents at a primary or secondary school.

(e) Filing a homeowner's property tax exemption.

(f) Renting or leasing a home for use as a residence.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(g) Declaration of residency to obtain a license or any other privilege or
benefit not ordinarily extended to a nonresident.

(h) Possession of a California driver's license.

(i) Other acts, occurrences, or events that indicate presence in the state is
more than temporary or transient.

http://www.dmv.ca.gov/pubs/vctop/d01/vc516.htm
從牌照的條文看起來，加州居民認定較寬的感覺。