The aquarium (Mediterranean) strain of Caulerpa taxifolia is listed as a Federal Noxious Weed by the United States Department of Agriculture (USDA) under the Federal Plant Protection Act. This listing prohibits importing it into the United States or transporting it across state lines, including through Internet trade. Violators of this law face a penalty of up to $250,000. USDA Penalties.
The US Postal Service prohibits mailing the aquarium strain of Caulerpa taxifolia, designated as a "non-mailable plant pest" under US Code Title 39, 3015. US Code Title 18, 1716D provides criminal penalties for mailing non-mailable plant pests. Caulerpa taxifolia is difficult to identify. The burdon is upon the sender to ensure that prohibited items are not being mailed.
California
California Fish and Game Code 2300 prohibits the sale, possession, importation, transport, transfer and release of nine species of Caulerpa: C. taxifolia, C. racemosa (Grape Caulerpa), C. ashmeadii, C. cupressoides, C. floridana, C. mexicana, C. sertulariodes, C. scalpelliformis, and C. verticillata within the state. This includes all Internet transactions of those species where the seller, owner, buyer, or recipient resides in California. Any person or pet shop that violates the code is subject to a civil penalty of not less than $500 and not more then $10,000 for each violation.
Oregon
The State of Oregon Department of Agriculture ODA Plant Division prohibits the transport, purchase, sale or propagation of Caulerpa taxifolia.
Alabama
The Alabama Department of Agriculture and Industries, Plant Protection Section lists the aquarium strain of Caulerpa taxifolia as a Class A Noxious Weed because it is on the Federal List.
Massachusetts
The Massachusetts Division of Regulatory Services, Bureau of Farm Products & Plant Industries, prohibits the sale, trade, purchase, distribution and related activities of Caulerpa taxifolia.
North Carolina
The North Carolina Department of Agriculture and Consumer Services, Plant Industry Division — Plant Protection Section lists the aquarium strain of Caulerpa taxifolia as a Class A Noxious Weed because it is on the Federal List.
South Carolina
The South Carolina Department of Natural Resources Aquatic Nuisance Species Program prohibits the possession, importation and distribution of Caulerpa taxifolia.
Vermont
The Vermont Department of Agricultural Resource Management and Environmental Stewardship lists the aquarium strain of Caulerpa taxifolia as a Class A Noxious Weed because it is on the Federal List and prohibits its importation, movement, sale, possession, cultivation and/or distribution.
The City of San Diego bans the sale, possession or transport of the entire genus of Caulerpa within city limits (City of San Diego Ordinance 18967).