"by intentional" is correct and can be used in written English
You may use it when talking about an action that was done purposely and on purpose. For example: "She arrived late to the party by intentional design."
Likewise, if I intend to skip breakfast and do so because I forget about it, my intention was fulfilled, though not by intentional action.
The sight of Pujols's bat being rendered useless by intentional walks has become increasingly familiar.
Police charged four officials with a range of offences, including causing death by intentional wounding.
In Baltimore, the killing of William Torbit, an officer of color, by intentional fire traumatized the agency.
The grisly discovery was made in a cave where scientists found bones bearing marks left by intentional butchering.
Human Rights Watch, which has also looked at the images, said that destruction of five ethnic Georgian villages near the South Ossetian capital of Tskhinvali "was caused by intentional burning and not armed conflict".
But Glen D. Nager, arguing for the company, said the phrase bolstered his view that "age has to be a but-for cause" and that the law was violated only by intentional discrimination on the part of the employer.
Interestingly, the transformation almost always occurs after exposure to different agents perceived as "dangerous" – Spider-man with an unintended bite by a transgenic spider, the Hulk by intentional exposure to external beam radiation.
It's keyed to a legal definition of rape which in many states includes sex obtained by intentional incapacitation of the victim with intoxicants the scenario envisioned by my father.
Prosecutors excluded blacks from juries for going to church too often or for other reasons that "simply make no sense" and that could be explained only by intentional and ugly bias.
Investigators searched air accident databases and found evidence of six public transport accidents whose conclusions show they were caused by "intentional manoeuvres by one of the flight crew members that was intended to lead to the loss of the aircraft and its occupants".
