Apparently nothing until he announced he was running for President.
From 1973 and until he was elected president in 2016, Donald Trump and his businesses were involved in over 4,000 legal cases in United States federal and state courts, including battles with casino patrons, million-dollar real estate lawsuits, personal defamation lawsuits, and over 100 business tax disputes.
In 1973, Trump was accused by the Justice Department of violations of the Fair Housing Act in the operation of 39 buildings. The department said that black "testers" were sent to more than half a dozen buildings and were denied apartments, but a similar white tester would then be offered an apartment.
In 1988, the Justice Department sued Trump for violating procedures related to public notifications when buying voting stock in a company related to his attempted takeovers of Holiday Corporation and Bally Manufacturing Corporation in 1986. Trump agreed to pay $750,000 to settle the civil penalties of the antitrust lawsuit.
In 2001, the U.S. Securities and Exchange Commission brought a financial-reporting case against Trump Hotels & Casino Resorts Inc., alleging that the company had committed several "misleading statements in the company's third-quarter 1999 earnings release".
In 2000, Donald Trump paid $250,000 to settle fines related to charges brought by New York State Lobbying Commission director David Grandeau. Trump was charged with circumventing state law to spend $150,000 lobbying against government approval of plans to construct an Indian-run casino in the Catskills, which would have diminished casino traffic to Trump's casinos in Atlantic City.
In 2013, in a lawsuit filed by New York attorney general Eric Schneiderman, Trump was accused of defrauding more than 5,000 people of $40 million for the opportunity to learn Trump's real estate investment techniques in a for-profit training program, Trump University, which operated from 2005 to 2011.
Trump University was later ordered by a U.S. district judge in April 2015 to pay Makaeff and her lawyers $798,774.24 in legal fees and costs. Donald Trump was found to have defrauded students and was forced to pay $25 million in restitution.
In 1991, one of Trump's casinos in Atlantic City, New Jersey, was found guilty of circumventing state regulations about casino financing when Donald Trump's father bought $3.5 million in chips that he had no plans to gamble. (runs in the family)
In 2006, the Town of Palm Beach began fining Trump $250 per day for ordinance violations related to his erection of an 80-foot-tall (24 m) flagpole flying a 15-by-25-foot (4.6 by 7.6 m) American flag on his property. Trump sued the town for $25 million, saying that they abridged his free speech, also disputing an ordinance that local businesses be "town-serving". The two parties settled as part of a court-ordered mediation, in which Trump was required to donate $100,000 to veterans' charities.
In 2003, the city of Stuttgart denied TD Trump Deutschland AG, a Trump Organization subsidiary, the permission to build a planned tower due to questions over its financing. Trump Deutschland sued the city of Stuttgart and lost. In 2004 Trump's German corporate partner brought suit against the Trump Organization for failure to pay back a EUR 2 million pre-payment as promised.
In April 1997, Jill Harth Houraney filed a $125,000,000 lawsuit against Trump for sexual harassment in 1993, claiming he "'groped' her under her dress and told her he wanted to make her his 'sex slave'".