People often mix up a declaration and an affidavit. Both are written statements of fact, but an affidavit is typically sworn before a notary or other authorized official, while a declaration is usually signed by the person making it under penalty of perjury without that formal notarization step. In plain terms, a declaration is a signed written statement used to present facts to a court, agency, or other decision-maker.

That difference matters because a declaration can be faster and easier to prepare when deadlines are tight. In a lawsuit, it may be used to support a motion, explain what a witness saw, or provide background about medical treatment, lost work, or how an injury limits daily activity. For someone recovering from a crash on black ice or a fall after a nor'easter, a declaration may help put practical facts in front of the court without waiting for a notarized affidavit.

In Massachusetts, courts and lawyers often use language stating that a declaration is made "under the pains and penalties of perjury." That wording gives the statement legal weight: if it is knowingly false, the signer can face consequences tied to perjury or credibility problems in the case. In an injury claim, that can affect settlement talks, motions, and how strongly the court views the evidence.