Decades-long

The proof of the futility of harsh drug laws is this: in the country that has come down the hardest on drugs and drug users, spending billions of dollars in a decades-long war on drugs, there have never been so many drug addicts.

Source: tatoeba (3678967)

War, disease, and famine continue to ravage the poverty-stricken country, despite the decades-long international effort to ameliorate the situation.

Source: tatoeba (5499396)

Donald Trump is the living reductio ad absurdum of the decades-long debate over "political correctness."

Source: tatoeba (5738610)