HB1963T Passed and was signed by Governor Parson on July 14th. Effective Aug 28th. Below is the wording pertaining to the NEW Modified Helmet Law .

Currently, every person operating or riding a motorcycle or motortricycle is required to wear protective headgear (Sections 302.020 and 302.026). This bill provides that persons under the age of 26 who are operating or riding as a passenger on a motorcycle or motortricycle shall wear a helmet when the vehicle is in motion. Similarly, a person who is 26 or older, is operating a motorcycle or motortricycle, and who has been issued an instruction permit shall wear a helmet when the vehicle is in motion. No political subdivision of the state shall impose a protective headgear requirement on the operator or passenger of a motorcycle or motortricycle. No person shall be stopped, inspected, or detained solely to determine compliance with these provisions (Section 302.020.2).
The bill also provides that qualified operators who are 26 or older may operate a motorcycle or motortricycle without a helmet if he or she is covered by a health insurance policy or other form of insurance which will provide the person with medical benefits for injuries incurred as a result of a motorcycle or motortricycle accident. Proof of such coverage shall be provided on request of law enforcement by showing a copy of the qualified operator’s insurance card. No person shall be stopped, inspected, or detained solely to determine compliance with these provisions (Section 302.026).