Plain language puts the message before anything else. It's another strategy to keep the focus off the writer and on the point the writer wants to make. The US federal government describes it like this:
Plain language (also called Plain English) is communication your audience can understand the first time they read or hear it.... No one technique defines plain language. Rather, plain language is defined by results—it is easy to read, understand, and use.
In practice, plain language might look like this:
Before: It is imperative that persons being transported in a motor vehicle utilize the vehicle's safety restraints, subject to the risk of severe bodily harm or injury, up to and including death.
After: When you're in a car you should wear a seatbelt. Not wearing a seatbelt is dangerous and you could die.
Before: During trial, Plaintiff-respondent admitted that both at the time the parties entered the 2007 Lease, providing additional basement space to Defendant-appellant, and continuously thereafter through and including September 2008 when Plaintiff-respondent admitted changing the locks and thereby evicting Defendant-appellant from the premises, the basement space that was the subject of the 2007 Lease had already been leased to another tenant in the building, namely a real estate office.
After: The landlord admitted it had leased the additional basement space to a different company before leasing it to the tenant. This was true when the landlord first signed the agreement to lease the additional space to the tenant in 2007 and it remained true for the lease's duration, until the landlord changed the locks in September 2008 and constructively evicted the tenant from the premises.
Before: ORDERED that the order entered February 24, 2016, is modified, on the law, by deleting the provision thereof, upon renewal, adhering to so much of the determination in the order dated August 3, 2015, as denied those branches of the motion of the defendant Richard D. Hong which were for summary judgment dismissing the first and second causes of action insofar as asserted against that defendant, and substituting therefor a provision, upon renewal, vacating that portion of the order dated August 3, 2015, and thereupon granting those branches of the motion.
After: The August 3, 2015, order in this case denied defendant Richard D. Hong's motion for summary judgment on the first and second causes of action. The motion was renewed and the trial court affirmed the denial in an order entered February 24, 2016. We now vacate the part of the February 24 order that affirmed denial of summary judgement, and grant Hong's motion on these causes of action.
Modern  English: Objective considerations of contemporary phenomena compel the conclusion that success or failure in competitive activities exhibits no tendency to be commensurate with innate capacity, but that a considerable element of the unpredictable must invariably be taken into account.
Plain-language original: I returned and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all. (George Orwell: ‘Politics and the English Language'. First published: Horizon. — GB, London. — April 1946.)
After slogging through the oppressive legal- and bureaucratese in the first versions, the crisp examples in the second are the written version of emerging from a humid steam room into a cold plunge pool. Here's a final example, from the world's best waiver and disclaimer:
But even though you might get hurt or lost, you’re agreeing to all this crap because you want to run this race. You are therefore releasing and discharging all race officials, volunteers, sponsors and municipalities, as well as the rocks, roots, bugs, tree limbs, and other stuff, dead or alive, gnarly or not, that might poke an eye out or otherwise hurt you. Because you know that trail running is a high-risk activity.
So how can you use plain language to simplify and clarify your own writing?
For lawyers who are comfortable with traditional bloated legal writing, simplifying words and arguments in a shift to plain language feels strange and almost condescending. But it doesn't come across that way. With practice, plain language results in clarity and quick understanding. In the example about the seatbelts above, which version is more likely for the reader to remember?
Several guides and checklists make plain-language strategies more accessible. For example, Appendix C of the Pennsylvania Plain Language Consumer Contract Act sets out principles mirrored by authors such as Strunk & White and Richard C. Wydick:
IV. GENERAL PRACTICE POINTERS
A. Use short words, short sentences and short paragraphs.
B. Use active voice.
C. Eliminate legalese such as: HEREBY, THEREOF, HERETOFORE, THEREAFTER.
D. Use familiar vocabulary.
E. Rephrase legal jargon into simple language.
F. Use names or pronouns consistently.
G. Define words by using commonly understood meanings.
George Orwell recommends the following straightforward list of rules:
i. Never use a metaphor, simile, or other figure of speech which you are used to seeing in print.
ii. Never use a long word where a short one will do.
iii. If it is possible to cut a word out, always cut it out.
iv. Never use the passive where you can use the active.
v. Never use a foreign phrase, a scientific word, or a jargon word if you can think of an everyday English equivalent.
vi. Break any of these rules sooner than say anything outright barbarous.
As helpful as checklists and other editing devices are, they require a lot of investment once the drafting is over. There's nothing wrong with that; after all, drafting is only a small portion of the final product. But another useful strategy, during the writing process itself, ensures that your legal writing audience will quickly grasp even convoluted arguments: Pretend you're writing to a bright 11th-grader, and your writing tends to fall into place.