In February 2003 Cisco Systems sued Huawei Technologies for allegedly infringing on its patents and illegally copying source code used in its routers and switches.[106] According to statement by Cisco, by July 2004 Huawei removed the contested code, manuals and command-line interfaces and the case was subsequently dropped.[107] Both sides claimed success – with Cisco asserting that "completion of lawsuit marks a victory for the protection of intellectual property rights", and Huawei's partner 3Com (which was not a part of lawsuit) noting that court order prevented Cisco from bringing another case against Huawei asserting the same or substantially similar claims.[108] Although Cisco employees allegedly witnessed counterfeited technology as late as September 2005,[109] in a retrospective Cisco's Corporate Counsel noted that "Cisco was portrayed by the Chinese media as a bullying multi-national corporation" and "the damage to Cisco's reputation in China outweighed any benefit achieved through the lawsuit".;[110] however the same article that quoted the remarks of the Corporate Counsel also notes the remarks of Jay Hoenig of Hill and Associates, a security and risk management consultancy, who encouraged foreign companies to take greater advantage of civil litigation and said that it was hard to make the argument that China's civil system was ineffectual if litigants did not pursue all of the legal remedies available to them.[110]

Huawei's chief representative in the US subsequently claimed that Huawei had been vindicated in the case, breaking an confidentiality clause of Huawei's settlement with Cisco. In response Cisco revealed parts of the independent expert's report produced for the case which proved that Huawei had stolen Cisco code and directly copied it into their products.[111]

In June 2004, a Huawei employee was caught after hours diagramming and photographing circuit boards from a competitor booth at the SuperComm tradeshow.[112] The employee denied the accusation, but was later dismissed.[113][114]

In July 2010, Motorola filed an amended complaint that named Huawei as a co-defendant in its case against Lemko for alleged theft of trade secrets.[115][116] The case against Huawei was subsequently dropped in April 2011

A U.S. Army Strategic Studies Institute report on Argentina published in September 2007 describes Huawei as "known to bribe and trap clients." The report details unfair business practices, such as customers framed by "full-paid trips" to China and monetary "presents" offered and later used by Huawei as "a form of extortion."[168]