As long as the plate is visible (no bends, not at an angle) and there is a light shining on it at night, you're fine. A lot of guys install a small LED light between the canisters which shines down on the license plate at all times as well.
Please don't mislead folks its never that simple and for WA it clearly can be up to the officer (SEE BOLD UNDERLINE)
*** sorry I should NOT say mislead I just want to point out every state is different, and no law is just a sentence. 99.9% if you are getting pulled over for something like this they are pulling you over for something else this was just the excuse of which as you can see can be easy...
All license plates may be obtained by the director from the metal working plant of a state correctional facility or from any source in accordance with existing state of Washington purchasing procedures. License plates:
(a) May vary in background, color, and design;
(b) Must be legible and clearly identifiable as a Washington state license plate;
(c) Must designate the name of the state of Washington without abbreviation;
(d) Must be treated with fully reflectorized materials designed to increase visibility and legibility at night;
(e) Must be of a size and color and show the registration period as determined by the director; and
(f) Before July 1, 2010, may display a symbol or artwork approved by the former special license plate review board and the legislature. Beginning July 1, 2010, special license plate series approved by the department and enacted into law by the legislature may display a symbol or artwork approved by the department.
(2) Exceptions to reflectorized materials.
License plates issued before January 1, 1968, are not required to be treated with reflectorized materials.
(3) Dealer license plates.
License plates issued to a dealer must contain an indication that the license plates have been issued to a vehicle dealer.
The director shall furnish to all persons making satisfactory application for a vehicle registration:
(i) Two identical license plates each containing the license plate number; or
(ii) One license plate if the vehicle is a trailer, semitrailer, camper, moped, collector vehicle, horseless carriage, or motorcycle.
(b) The director may adopt types of license plates to be used as long as the license plates are legible.
License plates must be:
(i) Attached conspicuously at the front and rear of each vehicle if two license plates have been issued;
(ii) Attached to the rear of the vehicle if one license plate has been issued;
(iii) Kept clean and be able to be plainly seen and read at all times; and
(iv) Attached in a horizontal position at a distance of not more than four feet from the ground.
(b) The Washington state patrol may grant exceptions to this subsection if the body construction of the vehicle makes compliance with this section impossible.
(6) Change of license classification.
A person who has altered a vehicle that makes the current license plate or plates invalid for the vehicle's use shall:
(a) Surrender the current license plate or plates to the department, county auditor or other agent, or subagent appointed by the director;
(b) Apply for a new license plate or plates; and
(c) Pay a change of classification fee required under RCW 46.17.310
(7) Unlawful acts.
It is unlawful to:
(a) Display a license plate or plates on the front or rear of any vehicle that were not issued by the director for the vehicle;
(b) Display a license plate or plates on any vehicle that have been changed, altered, or disfigured, or have become illegible;
(c) Use holders, frames, or other materials that change, alter, or make a license plate or plates illegible. License plate frames may be used on license plates only if the frames do not obscure license tabs or identifying letters or numbers on the plates and the license plates can be plainly seen and read at all times;
(d) Operate a vehicle unless a valid license plate or plates are attached as required under this section;
(e) Transfer a license plate or plates issued under this chapter between two or more vehicles without first making application to transfer the license plates. A violation of this subsection (7)(e) is a traffic infraction subject to a fine not to exceed five hundred dollars. Any law enforcement agency that determines that a license plate or plates have been transferred between two or more vehicles shall confiscate the license plate or plates and return them to the department for nullification along with full details of the reasons for confiscation. Each vehicle identified in the transfer will be issued a new license plate or plates upon application by the owner or owners and the payment of full fees and taxes; or
(f) Fail, neglect, or refuse to endorse the registration certificate, except as authorized under this section.
(a) Standard issue license plates must be replaced when ownership of the vehicle changes, pursuant to subsection (9)(a)(i) of this section, but the registered owner may retain the license plates and transfer them to a replacement vehicle of the same use. In addition to all other taxes and fees due upon change in ownership, a registered owner wishing to keep standard issue license plates shall pay the license plate transfer fee required under RCW 46.17.200
(1)(c) when applying for license plate transfer.
(b) Special license plates and personalized license plates may be treated in the same manner as described in (a) of this subsection unless otherwise limited by law.
(c) License plates issued to the state or any county, city, town, school district, or other political subdivision entitled to exemption as provided by law may be treated in the same manner as described in (a) of this subsection.
(d) License plate replacement is not required when a change in vehicle ownership is the result of one or more of the following circumstances:
(i) When adding a lien holder to the certificate of title or removing a lien holder from the certificate of title;
(ii) When a vehicle is transferred from one spouse or registered domestic partner to another;
(iii) When removing a deceased spouse or registered domestic partner from the certificate of title;
(iv) When a vehicle is transferred by gift or inheritance to one or more members of the registered owner's immediate family;
(v) When a vehicle is transferred into or out of a trust in which the registered owner or one or more immediate family members of the registered owner is the beneficiary;
(vi) When a leaseholder buys out the leased vehicle; or
(vii) When a person changes his or her name.