[26] In November 1981, Grassley was one of 32 senators to sign a letter to President Reagan supporting Director of the Office of Management and Budget David Stockman.

[27] In August 1982, while the Reagan administration tried persuading senators to approve legislation authorizing the creation of a radio station for broadcasting to Cuba, Grassley joined fellow Iowa senator Roger Jepsen and Edward Zorinsky in seeking an amendment to the bill barring the Reagan administration from operating Radio Marti on that frequency or other commercial AM frequencies.

Assistant Attorney General Stephen S. Trott called the citation "out of place" since Grassley was not acting at a session of the Judiciary panel he led.

Grassley's measure was also designed to unravel an accounting device lawmakers had used to make it appear that they were reducing spending for the incoming fiscal year.

[44] In January 1991, Grassley was one of only two Republican senators to vote against joining the international coalition to force Iraq out of Kuwait, the other being Mark Hatfield of Oregon.

[45] In August 1991, he became one of six Republicans on the Select Senate Committee on POW-MIA Affairs that would investigate the number of Americans still missing in the aftermath of the Vietnam War following renewed interest.

[46] In July 1998, President Bill Clinton listed Grassley among the members of Congress who had made it possible "for me to sign into law today the Internal Revenue Service Restructuring and Reform Act".

[49] In August 2002, Grassley sent a letter to president and chief executive of the United Way of America Brian Gallagher requesting a detailed explanation on the overseeing of both finances and management of the organization's affiliates.

Grassley also wrote to chief executive of the United Way of the National Capital Area Norman O. Taylor in regards to allegations of affiliates misappropriating money as well as withholding information the board needed to allow its conducting of oversight.

[50] As a senior member of the Senate Finance Committee, Grassley has spearheaded many probes into alleged misuse and lack of accountability of federal money.

[55] On June 28, 2006, Grassley proposed legislation[56][57] intended to curb sex trafficking and sexual slavery in the United States by means of strict enforcement of tax laws, for example by requiring a W-2 form be filed for each prostitute managed by a pimp or other employer.

Since 1976, Grassley has repeatedly introduced measures that increase the level of taxation on American citizens living abroad, including retroactive tax hikes.

Critics of the amendment felt that the move hurt Americans competing for jobs abroad by putting an unnecessary tax burden on foreign employers.

[75] On March 9, 2015, Grassley was one of 47 senators to sign a letter to Iran led by Tom Cotton to rebuke the Joint Comprehensive Plan of Action.

In 2020, after a Supreme Court vacancy arose due to Justice Ruth Bader Ginsburg's death, Grassley supported a prompt vote on Trump's nominee, backing the decision of "the current chairman of the Judiciary Committee and the Senate Majority Leader".

[99] In April 2019, Grassley was one of seven senators to sign a letter led by Debbie Stabenow and Joni Ernst to United States secretary of agriculture Sonny Perdue urging the Agriculture Department to implement conservation measures in the 2018 Farm Bill "through a department-wide National Water Quality Initiative, which would build off the existing initiative housed at the Natural Resource Conservation Service".

[110] On June 19, 2007, Grassley helped expand tax incentives that produces energy from alternative sources including ethanol, wind, biomass, and biodiesel.

[75] In 2016, one month after the Orlando nightclub shooting, Grassley proposed legislation to expand state-to-state access to background check data and to make it illegal for government officials to sell criminals guns as part of sting operations.

[125] Additionally, he voted against the Democrats' Feinstein Amendment, which would make it illegal to sell guns to individuals on the terror watchlist and a Republican-sponsored bill that expanded funding for background checks.

[128] A day after the Douglas High School shooting in Parkland, Florida, Grassley said the government had not done enough to prevent individuals with a mental illness from obtaining firearms.

[131][132][133] Grassley engaged in lengthy negotiations with the Obama administration, as it sought health care reform with support from Republican members of Congress.

[138] In August 2018, Grassley was one of ten Republican senators to cosponsor legislation intended to protect ACA provisions for people with preexisting conditions.

[141] Grassley has voiced objections to the Special Immigrant Visa program, which resettles translators and their family members who face risks to their lives due to their work with the U.S.

[152] Simpson is the co-founder of the political opposition research firm Fusion GPS, which produced the so-called Steele Dossier on alleged connections between Trump and Russia.

[152][153] In January 2018, Grassley was one of 36 Republican senators to sign a letter to President Trump requesting he preserve the North American Free Trade Agreement by modernizing it for the economy of the 21st century.

[162][163] After President Biden withdrew from the 2024 presidential race on July 21, 2024, Grassley posted on X, "The American ppl are sick & tired of the Biden-Harris open border policies + high cost of living crushing family budgets.

[164][165][166][167] On November 5, 2007, Grassley announced an investigation into the tax-exempt status of six ministries under the leadership of Benny Hinn, Paula White, Eddie L. Long, Joyce Meyer, Creflo Dollar, and Kenneth Copeland by the United States Senate Committee on Finance.

[172] Weeks later, Grassley alleged that Alan Schatzberg, chair of psychiatry at Stanford University, had underreported his investments in Corcept Therapeutics, a company he founded.

[174] Similarly, Charles Nemeroff resigned as chair of the psychiatry department at Emory University after failing to report a third of the $2.8 million in consulting fees he received from GlaxoSmithKline.

[193][194][195][196] In 2003, Grassley's alma mater, the University of Northern Iowa, selected him for honoris causa membership in Omicron Delta Kappa, the National Leadership Honor Society.