Plain language writing sets a testable goal for text: a reader gets the message on the first pass. Literacy scholars define it as communication an audience can understand the first time they read or hear it, per Wikipedia’s entry as updated in 2026. The field earns the word science through measurement, though parts of its evidence base remain thin.
The number came before the rules. In 1975, Rudolf Flesch and J. Peter Kincaid scored texts by word and sentence length and mapped the result to a United States school grade level, per Wikipedia’s entry. Their Flesch-Kincaid test still screens documents today. The site’s literacy coverage follows where text difficulty and reader skill meet.
Law followed the measurement. The United States required federal agencies to write plainly with the Plain Writing Act of 2010, and agency rewrites now swap clause stacks for short sentences. The same checking habit helps outside government, as in how to check a health claim in five minutes. It costs minutes and catches misreadings early.
What makes writing plain?
Wikipedia’s entry on plain language defines it as writing designed so the reader understands as quickly, easily, and completely as possible. It avoids jargon, padding, and convoluted construction. The editor Joseph Kimble cuts the idea shorter: clear and effective communication. It puts the audience first, so the same memo may be plain for a nurse and dense for a lawyer. Word count settles nothing on its own. The reader decides.
How is clarity measured?
The oldest tools are readability formulas. Flesch-Kincaid, created in 1975, predicts the schooling a text demands from word length and sentence length, per Wikipedia’s entry. Newer rules go further. The International Organization for Standardization published ISO 24495-1 in 2023, a plain language standard written by a working group formed in 2019. Formulas screen, they do not prove: a good score says nothing about whether the right facts made it onto the page. Official guides add design and testing to the count, from white space and bullets to trying drafts on real users.
Why did it become law?
President Bill Clinton pointed federal agencies toward plain writing in a 1998 memorandum, citing time, effort, and money saved, per Wikipedia’s entry on the Plain Writing Act. President Barack Obama signed the Act on October 13, 2010. It requires plain writing in covered documents, staff training, and a public channel for comment. The United Nations’ disability convention counts plain language as part of communication itself.
The government’s own guidance site, Digital.gov, states the stakes in plain terms: the public has to make sense of its obligations and benefits, and content for the public must be written for its specific audience. The same page notes that plain language is more efficient and effective, and that it is also the law.
Where the evidence comes from
The record mixes history, law, and lab work. Banks adopted the style early: Citibank rewrote its promissory notes in 1973 after lawsuits over bad debts, per Wikipedia’s entry. Consumer groups pushed similar rules for contracts and insurance that same decade. Comprehension studies support specific rewrites, but the entry notes that the broadest claims come mostly from proponents. A law’s effect is hard to isolate from other changes. The honest summary is mixed: testing works, and sweeping claims need care. The Center for Plain Language goes further, calling the style a civil right. This connects to our earlier piece, What works in adult literacy when school is long over.
Conclusion
Plain language earns the word science the way any applied field does. It states a goal, measures it, and revises when the test fails. The 1975 formulas, the 2010 Act, and the 2023 ISO standard mark that loop in dates. The style is only the packaging. The method is asking a reader what the text said, and trusting that answer over the writer’s intent.
