A letter of assurance is a formal, often legally binding document in which a person or organization promises to meet specific obligations, and courts have repeatedly treated these promises as enforceable contracts. You will most often see one in two settings: a patent holder committing to a standards organization that it will license its patents on reasonable terms, and a licensed engineer or architect certifying to a building department that a project’s design meets code. In both cases, the signer is making a commitment that outside parties can hold them to.
Where You Will Encounter One
The two dominant uses sit in very different industries but share a common structure: a written promise, made to an institution, that third parties end up relying on.
In technology standards, groups like the IEEE develop specifications for things like wireless networking. When a proposed standard would require the use of someone’s patented technology, the standards body asks the patent holder for a licensing commitment so the patent cannot later be used to hold the entire industry hostage. That commitment is the letter of assurance (LOA).1IEEE Standards Association. IEEE-SA Standards Board Bylaws
In construction, many jurisdictions require licensed architects and professional engineers to sign letters confirming that a building’s design meets applicable safety and structural codes. These letters shift the burden of code verification from local government inspectors to the professional who designed the work. If the building later fails to meet code, the professional who signed is personally on the hook.
Letters called “assurance letters,” “comfort letters,” or “business associate agreements” also appear in environmental enforcement under CERCLA and in HIPAA-regulated health care arrangements. Those are different instruments with different legal mechanics and are not covered here.
What an IEEE Letter of Assurance Commits the Signer To
Under Section 6.2 of the IEEE Standards Association bylaws, the IEEE requests an LOA from any patent holder whose technology may be essential to a standard under development. The holder is expected to submit the letter as soon as reasonably feasible after the project is approved, ideally before the Standards Board votes to finalize the standard. If more essential patents turn up later, a new LOA is required for them.1IEEE Standards Association. IEEE-SA Standards Board Bylaws
The form itself offers two licensing choices. The patent holder can commit to licensing without any compensation at all, or it can agree to license at reasonable rates free of unfair discrimination. If it picks the reasonable-rate option, it may specify a maximum rate, such as a flat fee per unit or a percentage of the product price. Either way, the holder commits to license an unlimited number of applicants worldwide.2IEEE-SA Standards Board. Letter of Assurance for Essential Patent Claims
The submitter can list specific patent numbers or file a blanket LOA covering all essential patent claims it currently holds or may hold in the future for that standard.2IEEE-SA Standards Board. Letter of Assurance for Essential Patent Claims The blanket version is simpler, but it also locks the submitter into commitments covering patents it has not yet identified.
Participants in the standards process carry their own duty. Anyone personally aware of a patent that could be essential to the standard being developed must either tell the IEEE or make sure someone else does. The duty covers patents the participant or their employer owns or controls.1IEEE Standards Association. IEEE-SA Standards Board Bylaws
What a Construction Letter of Assurance Commits the Signer To
Construction LOAs are typically organized by project stage. At the permit application phase, a letter identifies the coordinating professional responsible for the project. Before construction begins on individual building components, separate letters confirm which registered professionals are responsible for design and field review of each component. After construction wraps up, and before an occupancy permit is issued, final letters confirm that all design and field review obligations were fulfilled. The result is a documented chain of accountability from initial design through completed building.
The professional who signs must hold a valid license and typically applies a professional seal or stamp with the registration number clearly visible. The letter is filed with the local building department and becomes part of the permanent permit record. Signing one is a serious act: the professional is staking their license and personal liability on the claim that the work meets code.
Is a Letter of Assurance Enforceable?
Yes. In both the patent and construction settings, courts and licensing bodies have treated these letters as binding, and the enforceability extends beyond the institution that received the letter.
For IEEE patent commitments, once an LOA is accepted it is irrevocable. The commitment runs from the date the standard is approved until the standard is withdrawn, and the patent holder cannot take it back.3IEEE Standards Association. Letter of Assurance for Essential Patent Claims That permanence is the point. Companies designing products around a standard need to know the licensing promise will last the life of the standard.
Federal courts have confirmed that these commitments create real contracts. In Microsoft Corp. v. Motorola, Inc., the Ninth Circuit upheld a lower court finding that Motorola’s commitments to license its standard-essential patents on reasonable, non-discriminatory terms were binding contractual obligations. The court went further: Microsoft, a company that used the standard, could enforce those commitments as a third-party beneficiary even though it had no direct agreement with Motorola.4United States Court of Appeals for the Ninth Circuit. Microsoft Corp. v. Motorola, Inc., 795 F.3d 1024 (9th Cir. 2015) The ruling matters because it means any company implementing the standard can hold the patent holder to its LOA, not just the standards organization.
A related question is what happens when a covered patent is sold. Legal scholars and several courts have taken the position that a licensing commitment made to a standards organization runs with the patent, so the new owner inherits the obligation. A company cannot escape its promise by selling the patent to an entity that never signed an LOA. The law is still developing here, but buyers of standard-essential patents should assume the commitment transfers with the asset.
For construction letters, enforceability shows up through state licensing boards and civil courts rather than through contract litigation. A board can revoke or suspend the registration of an engineer or architect who certifies work that does not meet code, and the signer can face personal liability in lawsuits if a building defect causes injury or property damage.
What Happens If an Assurance Is False or Breached
Submitting a false letter of assurance to a federal agency can trigger criminal prosecution. Under 18 U.S.C. ยง 1001, anyone who knowingly makes a materially false statement in any matter within the jurisdiction of the federal government faces up to five years in prison and substantial fines. The statute covers written documents, oral statements, and deliberate omissions. The statement must be material, meaning capable of influencing the agency’s decision, and the government must prove the person knew the statement was false and intended to deceive.5Office of the Law Revision Counsel. 18 USC 1001 – Statements or Entries Generally
In the standards context, breaking a licensing commitment can produce both contract and antitrust exposure. A patent holder that signs an LOA promising reasonable licensing terms and then refuses to honor those terms, demands excessive royalties, or seeks an injunction to block competitors from using the standard faces breach-of-contract claims from any company implementing that standard. If the breach also involves leveraging monopoly power to inflate prices or exclude competitors, it may violate the Sherman Act or Clayton Act. Courts have blocked patent holders from pursuing injunctions or import bans against standard users when the holder had made a licensing commitment it was not honoring.4United States Court of Appeals for the Ninth Circuit. Microsoft Corp. v. Motorola, Inc., 795 F.3d 1024 (9th Cir. 2015)
For construction professionals, signing a letter of assurance that turns out to be inaccurate opens the door to professional discipline, civil liability, and potential loss of licensure. The licensing consequences and the lawsuit exposure can arrive at the same time.
The Insurance Gap That Catches Professionals Off Guard
Professional liability insurance is built to cover claims of negligence, meaning situations where the professional failed to meet the accepted standard of care. It is not built to cover guarantees or warranties, and most professional liability policies contain an explicit exclusion for liability arising from express warranties or contractual guarantees. A letter of assurance, by its nature, looks a lot like a guarantee that specific conditions have been met or will be met.
The practical consequence: if a claim against you is grounded in your LOA rather than ordinary negligence, your insurer may deny coverage for that portion of the claim. You could end up funding a settlement or judgment from your own pocket or your firm’s assets. Review the policy language carefully before signing any document that could be read as a warranty, and talk to your insurer about where coverage ends. The safer drafting approach is to have the letter speak to code compliance rather than guarantee any particular outcome or level of performance.
Signing and Filing One
Whichever setting you are in, the signer must have actual authority to bind the organization to the terms. For IEEE patent matters, that means someone whose title indicates responsibility for intellectual property or legal affairs.6IEEE Standards Association. Standards Board Operations Manual – Clause 6 For construction, it means a licensed professional engineer or architect with a current registration. Corporate submissions generally require an officer with authority to commit the company.
Use the current form. Standards organizations and building departments update their forms periodically, and submitting an outdated version is one of the more common reasons for rejection. The IEEE posts its current LOA form through its PatCom materials page.7IEEE Standards Association. PatCom Patent Materials Building departments issue their own jurisdiction-specific forms.
Filing methods vary. IEEE LOAs can be submitted by email, fax, or mail; once accepted, they are posted on the IEEE SA public website so any potential licensee can see them.6IEEE Standards Association. Standards Board Operations Manual – Clause 6 Construction letters are filed with the local building department, with some jurisdictions accepting digital submissions, and they become part of the permanent permit file.
Keep a copy of every LOA you file, along with any acknowledgment of receipt. If a dispute arises later, those records are your evidence of what you committed to and when.