Samsung is in hot water with an Australian regulator over adverts for its Galaxy phones.
They show people using the phones underwater and in the sea.
The Australian Competition and Consumer Commission (ACCC) alleges the South Korean company made "false, misleading and deceptive representations" about the water resistance of various 'Galaxy' branded phones.
The watchdog said it is not known if the phones can be used in all types of water.
Samsung says it intends to defend the court proceedings.
Since around February 2016, Samsung has widely advertised on social media, online, TV, billboards, brochures and other media that the Galaxy phones are water resistant and depicted them being used in, or exposed to, oceans and swimming pools.
Samsung also advertised the Galaxy phones as being water resistant up to 1.5 metres deep for 30 minutes.
The ACCC's case involves over 300 advertisements.
News: Samsung in court for misleading phone water resistance advertisements https://t.co/I80afuWcJh— ACCC (@acccgovau) July 4, 2019
ACCC chair Rod Sims says: "The ACCC alleges Samsung's advertisements falsely and misleadingly represented Galaxy phones would be suitable for use in, or for exposure to, all types of water, including in ocean water and swimming pools, and would not be affected by such exposure to water for the life of the phone, when this was not the case".
The ACCC claims Samsung did not have a reasonable basis for making the representations because "it did not test or know of testing (or sufficient testing) about how exposing a Galaxy phone to water (including non-fresh water) affected its usable life".
It also believes that the using of Galaxy phones in liquid other than fresh water could damage them.
For example, Samsung's website states that the new Galaxy S10 phone range is 'not advised for beach or pool use'.
"Samsung itself has acknowledged that water resistance is an important factor influencing Australian consumer decisions when they choose what mobile phone to purchase," Mr Sims says.
Galaxy phones which were advertised as being water resistant were also sold at a higher price than those which do not have the feature.
"Samsung's advertisements, we believe, denied consumers an informed choice and gave Samsung an unfair competitive advantage.
"Samsung showed the Galaxy phones used in situations they shouldn't be to attract customers," Mr Sims adds.
The ACCC is seeking penalties, consumer redress orders, injunctions, declarations, publication orders, an order as to findings of fact, and costs.
In a statement, Samsung Electronics Australia says it intends to defend the court proceedings.
"Samsung stands by its marketing and advertising of the water resistancy of its smartphones.
"We are also confident that we provide customers with free-of-charge remedies in a manner consistent with Samsung's obligations under its manufacturer warranty and the Australian Consumer Law."